Previously I had used the SH-56 multi-release cleats, but had encountered instances of coming unclipped when I didn't intend to. Was buying new shoes and decided to try the SH-51 cleats this time. The connection feels much more secure than the multi-release version, but still easy enough to clip in/out.
If you're new to clipless or commuting with a lot of stop-and-go then SH-56 might be better, but otherwise I would recommend the SH-51.
I have these cleats attached to my Shimano winter biking boots. Very effectively, no unexpectedly sliding around with the pedals & no problems having them get stuck in place when I stop at lights. So no fear of falling over (because of cleats & bike shoes in any case.
No complaints. I don't know how long they will last but they seem to be holding up better than the cleats I used when I had Crankbrothers eggbeaters. I put them on my Lake Boots and on my Sidi Mtn Bike shoes in about 10 minutes.
Each time I get a new pair of cycling shoes, new cleats get installed. They are cheap, and get the job done. I am tired of messing with my old used cleats- usually the bolts are all janky and gunked, thus the reason it's nice to install new ones.
IN THE WORLD OF CYCLING THE SKY'S THE LIMIT IN ALL CATAGORIES OF COMPONENTRY BUT THESE LITTLE BEAUTIES ARE IN MY OPINION THE BEST A CYCLIST CAN GET. I DO A LOT OF COMMUTING, TOURING AND EVERYTHING UNGER THE SUN ON MY BIKES AND I NEED TO BE ABLE TO WALK AROUND WHEN I'M OUT AND ABOUT. MTB SHOES GIVE ME 95% OF THE PERFORMANCE THAT ROAD SHOES OFFER AND A GOOD 500% MORE COMFORT OVER ROAD SHOES. I HAVE A FEW BIKES ALL OF WHICH COST OVER FOUR THOUSAND DOLLARS BUT I ALWAYS USE MTB SHES FOR COMFORT. I LIKE SHIMANO XTR TRAIL PEDALS AND HAVE THEM ON ALL MY BIKES. UNLESS YOUR A PRO RIDER ROAD SHOES AREN'T NECCESSARY IN MY HUMBLE OPINION. THESE ARE CHEAP CLEATS AND WORK EVERY TIME, BIG FAN OF THEM!!!