<---rank beginner MTB here and I use the double sided Shimano SPDs on my MTB. One side is clipless, the other side is flat with a cute little spot for my cleat to fit. I Love them on my MTB coz when I'm cruising along feeling very good and comfortable, I can be clipped in. If I see something coming that looks scary to me, I can unclip, flip the pedal over and ride on the flats (coz I promise you I'll fall!)

currently my falls to rides ratio is 2:1!