4"X 3/8"-24 BLACK PLASTIC BACKING PLATE ( includes Retainer nut)

$4.38 $6 In stock

The 4" x 3/8"-24 black plastic backing plate from Supergrit Abrasives includes a retainer nut. It is rated for a maximum speed of 20,000 RPM and is made for Porter Cable USA tools.

Size: 4 inches in diameter
Thread: 3/8"-24
Color: Black plastic backing plate
Includes: Retainer nut
Maximum speed: 20,000 RPM
Made for Porter Cable USA
Available as a single unit or in packs of 2, 5, or 10

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Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

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Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

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United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

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Customer Reviews (4.6 / 5 · 5 reviews)

Benjamin V. ★★★★★ Oct 21, 2026

This 4-inch plate fit perfectly on my Porter Cable sander, and the included retainer nut saved me a trip to the hardware store. The plastic feels sturdy enough for my daily use, and I’ve had no wobble at 10,000 RPM.

Elizabeth L. ★★★★★ Oct 20, 2026

Finally, a backing plate that actually stays put—the included retainer nut makes swapping pads so much easier. Fits my buffer perfectly right out of the box.

Owen P. ★★★★★ Oct 18, 2026

Swapped out the old worn backing plate on my sander, and this plastic one fit perfectly with the included retainer nut—nice not to hunt for extra hardware. Handles the 20,000 RPM just fine without any wobble.