SPD single release cleats, recommended for all MTB SPD pedals except PD M858
These are the single release cleats designed to work with Shimano SPD pedal systems where the foot is released by twisting it sideways.
The cleats sit recessed in the sole of the shoe allowing the rider to walk around which when off road can be important for negotiating obstacles and difficult terrain. They still give a solid fixing to the pedal allowing the rider to pull and push and so getting more power and more control through the pedal stroke. They are easy to clip into and one simple movement of the foot sideways will release the shoe.
The Shimano SPD pedal systems have become so popular that the term SPD is now widely used to describe an MTB pedal system, even if Shimano are not the manufacturers.