Rocky's Roller 323 In-Ground Swimming Pool 21' ft Replacement AT-1 Tube Set

Measures 3" in diameter Fits covers up to 20′ wide and extends to a width of 21′ 12 sided design to increase lateral integrity Light weight but rigid to prevent saggingYou may also like Unicel C-7488 Replacement 106 SqFt Pool Filter Cartridge (4 Pack).