Pretty strong suction, a little hard to first get it to suction on but once it’s on it’s really strong. Once I figure out more of the settings on that I know it will be great. I was so sure that the entire thing was going to fall forward on me during my first attempt at a pull-up. A little background - I have been an esthetician for over 20 years and am also a beauty writer, so I get to try the latest “it” products for free. I have no idea why Amazon want me to rate Sheerness and Thickness for a memory board! Im not sure where the other reviewer gets "functionally useless". there is plenty of worthy competition at this price point that should be considered. THESE SHOES ARE NOT WATERPROOF. Look at the shoes you plan to put these into and use the euro number - not the American size. Its great!