Anti-Slip Design: The doorstops of are made of soft silicone, designed with a grooved bottom surface, to hold doors firmly in place and prevent them from sliding or sliding shut. Height Adjustable : 6 door stops can be stacked together to fit maximum gaps of up to 60mm, 1 door stopper could at minimum gaps of 2mm.PLEAZE measure the height from the bottom of your door to the floor before buy! Safe, Eco-Friendly and Durable: Door Stops is non-toxic, odorless, door stoppers are made of superior silicone rubber to confirm for safe use. Universal Application :Can be easily inserted into door gaps,Suitable for all surfaces, carpets, concrete, tiles and wood.Wooden doors, metal doors, glass doors etc.