ADG Bipod Feet that have replaceable spikes for additional grip on a variety of surfaces. They have developed both a single spike version and a quad spike version. The single spike has a single central spike with a semi-domed basic shape that will grab softer surfaces like earth and grassy areas with or without a spike installed. The quad spike version has a multi-edge shape that will grab onto multiple points on hard surfaces both with and without spikes installed. ADG Bipod Feet come with a set of 1/4" spikes installed, a spike socket, and all necessary installation hardware.