{"product_id":"1-4-thick-5-25-od-round-aluminum-backing-plate-4-through-holes-center-vent-marine-grade-6061-t6","title":"1\/4\" Thick 5.25\" OD Round Aluminum Backing Plate | 4 Through-Holes + Center Vent | Marine Grade 6061-T6","description":"\u003cp style=\"font-size:1.15em;line-height:1.4;margin-bottom:0.75em;text-transform:none;color:#4a7ab5\"\u003e\u003cstrong\u003e5.25\" OD Round Backing Plate with Center Weld Vent\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003ePrecision CNC-machined 6061-T6 aluminum round backing plate with four through-holes and a center vent. Designed as the backside of a sandwich assembly on fiberglass pedestal walls in saltwater marine environments. Four through-holes allow fasteners to pass through and accept nuts on the back side, while the center vent provides weld gas release during installation. Pairs with \u003ca href=\"\/products\/1-4-thick-5-25-od-round-aluminum-countersunk-pad-4-countersunk-holes-center-vent-marine-grade-6061-t6\" style=\"color:#4a7ab5;text-decoration:underline\"\u003eSKU 1020 Countersunk Pad\u003c\/a\u003e for a matching hole pattern. Commonly used on top or through the side of a deck pedestal, as well as through the fiberglass skin of a hardtop or T-top.\u003c\/p\u003e\n\n\u003ctable style=\"font-size:0.9em;border-collapse:collapse\"\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eMaterial\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003eMarine Grade 6061-T6 Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eOutside Diameter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e5.25\" (133 mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eThickness\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e1\/4\" (0.250\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eThrough-Holes\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e4 (25\/64\" dia. for 3\/8\" fasteners)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eCenter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e1 vent hole (weld gas release)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003ePairs With\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e\n\u003ca href=\"\/products\/1-4-thick-5-25-od-round-aluminum-countersunk-pad-4-countersunk-holes-center-vent-marine-grade-6061-t6\" style=\"color:#4a7ab5;text-decoration:underline\"\u003eSKU 1020\u003c\/a\u003e (matching CS pad)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eShape\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003eRound\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eFinish\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003eMatte — tumbled, deburred, paint\/powder coat ready\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"background-color:#1a1a1a;text-transform:none;color:#ffffff;border:1px solid #ffffff\"\u003e\u003cstrong\u003eWeight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"font-weight:400;border:1px solid #ffffff\"\u003e0.46 lb\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003cp style=\"text-transform:none;font-weight:600;font-size:1.05em;color:#4a7ab5\"\u003eCommon Applications\u003c\/p\u003e\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003eT-tops, tuna towers, hard tops, radar arches, leaning posts, grab bars — commonly used on top or through the side of a deck pedestal, as well as through the fiberglass skin of a hardtop or T-top.\u003c\/p\u003e\n\n\u003cp style=\"text-transform:none;font-weight:600;font-size:1.05em;color:#4a7ab5\"\u003eFrequently Asked Questions\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eWhat is a backing plate?\u003c\/strong\u003e\u003cbr\u003e\nA backing plate reinforces the inside of a fiberglass pedestal wall. Fasteners pass through the exterior pad and the pedestal wall, and nuts thread onto the fastener behind the backing plate to lock the assembly in place.\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eWhat is the center vent hole for?\u003c\/strong\u003e\u003cbr\u003e\nThe center vent hole allows trapped air and gases to escape during welding, preventing blow-through and ensuring a clean, full-penetration weld.\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eWhy four holes instead of three?\u003c\/strong\u003e\u003cbr\u003e\nFour-hole patterns provide additional fastener points for heavier-duty mounting applications — radar mounts, outrigger bases, and multi-axis load points on T-tops and hard tops.\u003c\/p\u003e\n\n\u003cp style=\"font-weight:400;font-size:0.9em\"\u003e\u003cstrong\u003eWhat size fasteners work with this plate?\u003c\/strong\u003e\u003cbr\u003e\nThe four through-holes are 25\/64\" diameter, sized for 3\/8\" fasteners. Use 3\/8\"-16 stainless hardware with matching nuts for best results.\u003c\/p\u003e\n\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"Product\",\n      \"name\": \"1\/4\\\" Thick 5.25\\\" OD Round Aluminum Backing Plate | 4 Through-Holes + Center Vent | Marine Grade 6061-T6\",\n      \"sku\": \"1019\",\n      \"mpn\": \"1019\",\n      \"brand\": { \"@type\": \"Brand\", \"name\": \"Welding World\" },\n      \"description\": \"5.25 inch round aluminum backing plate with 4 through-holes and center vent. 1\/4 inch thick, 6061-T6, 25\/64 inch hole diameter for bolted assemblies on fiberglass decks. Pairs with SKU 1020.\",\n      \"material\": \"Aluminum 6061-T6\",\n      \"category\": \"Marine Deck Hardware\",\n      \"offers\": { \"@type\": \"Offer\", \"price\": \"22.00\", \"priceCurrency\": \"USD\", \"availability\": \"https:\/\/schema.org\/InStock\", \"seller\": { \"@type\": \"Organization\", \"name\": \"Welding World\" } }\n    },\n    {\n      \"@type\": \"FAQPage\",\n      \"mainEntity\": [\n        { \"@type\": \"Question\", \"name\": \"What is a backing plate?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"A backing plate reinforces the inside of a fiberglass pedestal wall. Fasteners pass through the exterior pad and the pedestal wall, and nuts thread onto the fastener behind the backing plate to lock the assembly in place.\" } },\n        { \"@type\": \"Question\", \"name\": \"What is the center vent hole for?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"The center vent hole allows trapped air and gases to escape during welding, preventing blow-through and ensuring a clean, full-penetration weld.\" } },\n        { \"@type\": \"Question\", \"name\": \"Why four holes instead of three?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"Four-hole patterns provide additional fastener points for heavier-duty mounting applications — radar mounts, outrigger bases, and multi-axis load points on T-tops and hard tops.\" } },\n        { \"@type\": \"Question\", \"name\": \"What size fasteners work with this plate?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"The four through-holes are 25\/64 inch diameter, sized for 3\/8 inch fasteners. Use 3\/8-16 stainless hardware with matching nuts for best results.\" } },\n        { \"@type\": \"Question\", \"name\": \"Does this backing plate have a matching countersunk pad?\", \"acceptedAnswer\": { \"@type\": \"Answer\", \"text\": \"Yes — SKU 1019 pairs with SKU 1020, a 1\/4 inch thick 5.25 inch OD round countersunk pad with the same 4-hole pattern and center vent. The backing plate goes on the inside of the pedestal wall; the countersunk pad goes on the outside for a flush-mount finish.\" } }\n      ]\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"Welding World, Inc.","offers":[{"title":"Default Title","offer_id":42976216350781,"sku":"Part Number: 1019","price":24.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0494\/7717\/files\/00161.png?v=1779211198","url":"https:\/\/weldingworldinc.com\/products\/1-4-thick-5-25-od-round-aluminum-backing-plate-4-through-holes-center-vent-marine-grade-6061-t6","provider":"Welding World, Inc.","version":"1.0","type":"link"}