CHECK SIZE BEFORE PURCHASE - Suitable for Round Tube from 0.63' to 0.71' (16-18mm); Tube End Cap Thread Diameter: 18mm/0.71'; Package Include: 8pcs Tube Inserts; WARM TIPS: PLEASE MEASURE THE SIZE OF YOUR CHAIR LEGS CAREFULLY BEFORE BUYING FLOOR PROTECTOR - This tube insert protect your beautiful hardwood, ceramic tile and vinyl plank floor from marring and scratches REDUCE NOISE - This tube insert can greatly reduce the noise, you should no more worry about suffering a harsh sound when moving the chairs and tables EASY INSTALLATION - For easy installation, each tube insert comes with ribs, only requiring lining up with the tube before tapping it into position. Ribs provide a secure fitting and to prevent the need for additional adhesives The size is slightly larger than what you need? Do not worry about it. Just cut a bit of the ribs to fit the application leg. If you have any problems about the size, please contact us by email