+3 BRT MarkBlue Gas Tube - Midlength GT-1-MID $15.95 In stock Quantity: 1 Add to Bag Product Details The Black River Tactical MarkBlue Gas Tube is a premium quality gas tube used to complete an AR with a mid length gas system. The distinctive "MarkBlue" dot allows easy identification of a genuine BRT gas tube and guaranteed performance. It is compatible with BRT MicroPin Gas Blocks, front site bases and low profile gas blocks. Includes a stainless steel gas tube and a stainless steel spiral coil spring pin. Save this product for later Favorite