These are the cleats that come with your Shimano SPD Pedals. The SH-51 Cleats are black and have four degrees of float for your feet. Compared to the SH-56 multi-release Cleats, these are much more secure and are generally preferred for the experienced rider. To get out of your pedal, you'll have to swing your heel out a bit more than the SH-56 Cleats. Please Note: These will not work with older PD-M858 pedals (for those you'll need SH-52 Cleats). On that same note, if you have an aftermarket SPD-style pedal that isn't a Shimano branded pedal, these cleats are most likely not compatible with your pedals even though they might look remarkably similar to a Shimano pedal.
Four degrees of float
Slightly greater release angle than Multi-Release Cleats