For use with all types of floating floors, these spacers are easily adjusted from 3/16" to 13/16" by turning the red dial. The 3-1/2" spacer width and self-locking feature of the dial mechanism means these spacers will not fall over or collapse, like loose wedge spacers. Placed on the floor being installed, the spacers are 1/2" high and are designed to make wall contact above any wall to subfloor gap. The spacer lip is angled slightly toward the floor edge, and has a grooved contact surface to hold the spacer firmly in place and prevent it from being accidentally forced out. To remove the spacer, simply turn the dial counterclockwise. Made of glass fiber reinforced plastic for excellent strength and durability, the spacers are sold four per set.