The service/fee is for a single taper pin. Please select Coiled Pin in the drop down if you would prefer a Coiled Pin . Some of the larger bore calibers(.458 and such) do not allow enough room to safely pin gas blocks. If your barrel is not dimpled, a locating dimple is included in the cost. The block will be aligned perfectly with the gas port, which is not always perfectly centered. All you need to send is the barrel and gas block. You can send a complete upper, but a disassemble – reassemble fee may apply if the gas block is not accessible. If you include your barrel nut we will be happy to slide it on before pinning the gas block.