CMI Crack Tacks were postage stamp size pitons available from the mid to late 1960s through the late 1970s. Their basic design was similar to the bigger knife blade style pins from Chouinard but, due to their smaller size, the perpendicular eye could limit placement in some situations. Crack Tacks really worked best in horizontal placements where the perpendicular arm could provide a bit of support and prevent the piece from levering out. These pitons were usually slung with half inch tie-off webbing or thin cord. Placements were almost always for direct aid and were “body weight” only.
Vertical Archaeology currently has these two, size 21 and 22, but there was also a size 20 in the same design.
Several photos with an early 1970s RURP and a Clog Micro are included.