The SH51 SPD single-release cleats are recommended for all mountain bike (MTB) SPD pedals except PD M858: release the cleat by twisting the heel outwards. In layman’s terms, this is the cleat that will fit 99% of SPD-compatible pedals excluding the PDM858.
The SH56 SPD is designed to work with all open design pedals: allow your shoe to be disengaged by rolling or twisting the foot in any direction
Depending on your requirements, Shimano MTB Cleats should have an option that can provide a solution for you.
