Removable stainless steel fastener for making fence panels, barn and garage siding from electro galvanized steel. Powerful at <90psi, my only complaints about the depth adjustment is not tool-free and the magazine cover is plastic. For the price I expect a little more in return. Ouch! and no cover? Even other Stanley brands offer you something to protect your investment. Other than that, it's a great tool. Manufacturer's suggestions. Tool-less depth adjustment, aluminum (t6) or steel (spring