Check the listing for details. Set Screws, Nylon Tip, 1/4-28 x 1/2" Thread Length, 10 PC Upper Lower Retention. Condition: New. Listed at 9.00 USD. Alloy Steel Set Screws, Nylon Tip, 1/4-28 x 1/2" Thread Length, 10 Pieces Nylon Tip Diameter .125"Nylon Tip Height .063"Thread Length .500"Overall Length .563"Nylon Tip is Non Conductive and has a temperature range is –50° to 250° F.Hex socket This Nylon Tipped Set Screw allows users to remove “slop” and fine tune the fit of their upper with their lower receiver. Achieve a tight fit with any standard AR-15 upper receiver by inserting the screw into the grip tang of any Lower Receiver that comes equipped with a vertical 1/4″ – 28 threaded hole and tightening against the upper receiver until there is no wobble between the 2 parts.Designed to be used with lower receivers that are drilled and tapped with a 1/4"-28 threaded hole.Works on AR15 and AR10 Style Rifles RETURN'S Where we are at fault. Item not as described, damaged or an obvious error on our part is guaranteed a full refund, inclusive of any & all shippingper our stated directions. RETURN DIRECTION’s; All returns MUST be in the original condition received. All returns MUST be shipped in the same manner as we shipped originally. ANY ADDITIONAL COST UP & BEYOND THE ORIGINAL COST, INCURRED IN RETURNING YOUR ITEM IS NOT REFUNDABLE. (if you choose to return an item at a higher rate than we originally shipped to you? This portion is NOT refundable) Refunds due because of a no error on our part are completed asan item refund only. Shipping is excluded. PLEASE feel free to contact us with any questions or concerns, as we strive for 100% satisfaction & happy customers. Items with a free shipping 20% restocking fee will apply.