For hard floor:· WARM TIPS:· These mats may be rolled when packaged. In such cases, the PVC material may take a few hours to return to its original shape once unpacked.· The mat should be placed smooth side down (facing the floor), textured side up.PLEASE FOLLOW BELOW STEPS:· Spread chair mat, begin to roll back from the front direction, put a night, it will naturally flat out.· Put books in each corners and the mat will be flat out after about 8 hours.· Or get some warm water to make it soften, spread it to the opposite direction down.SPECIFICATIONS·Material: PVC·Thickness: 2.2 mm·Shape: Rectangular·Color: ClearSize:30*48 inches