Protects against sun, snow, ice and wind. 4-feet overlap to fit most top rails. Heavy duty cable and winch tightener included. Pool size: 12-feet round. Cover size: 16-feet round. Pool size: 15 feet. Cover size: 19 feet. Pool size: 18-feet round. Cover size: 22-feet round. Pool size: 21-feet round. Cover size: 25-feet round. Pool size: 24 feet. Cover size: 28 feet. Pool size: 28 feet. Cover size: 32 feet. Cover size: 30 feet round. Pool size: 33 feet. Cover size: 37 feet.