These Facet Tech Feet are designed to be challenging as footholds. They allow route setters to force technical foot moves on any angle wall, though they shine on walls ranging from slab to slightly overhanging. The deepest edge to stand on is 1/4" while most are in the +/- 1/8" range. The edges also taper so just a little rotation of the hold changes the difficulty plus forces the climber to work on the eye-foot coordination.
For the full set, check out the 30 Super Small TECHNICAL Feet (Facets)