+3 BRT Gas Tube Pins ( 3 pcs ) GT-PINSx3 $4.95 In stock Quantity: 1 Add to Bag Product Details Replacement coil pins used to install a BRT MarkBlue Gas Tube. The Black River Tactical Gas Tube Pin is a premium quality stainless steel spiral coil spring pin. This easy to install pin allows you to replace a missing or damaged gas tube pin. The replacement pack includes Qty. (3) stainless steel spiral coil pins. Save this product for later Favorite