Apply to smooth floors such as tiles floor & any other smooth floors. Make sure the floor and the sucking pad are clean before using, then place. the suction cup on a smooth surface, make sure there are no gaps at the bottom. Couldn't Multi-functional sit up bar, a set of equipment can carry out a variety of sports, such as sit-ups, flat support, push-ups and so on. Use on Wooden Floors If you can ensure there no gaps on this floor or it very clean when you use this sit up bar on wooden floor. Four levels height adjustment meet different needs, all family members can use it. How to use: Step 1.Choose smooth ground Step 2.Clean the floor suction cup Step 3.Sucker installation Step 4.Height adjustment