I know these are designed for use on a typical angled peg board, but I also find them to be fun to use with footholds on a vertical wall. Allows for longer, endurance focused training, especially if you use one of the thicker diameter Atomik peg bombs. My kids (4 & 7) can easily use these on a vertical wall with the standard size pegs and footholds. As mentioned elsewhere, the slightly loose fit of the peg in the receiver allows for some rotation of the peg, which enhances the workout because you must stabilize to compensate.