Jandy CV Series Cartridge Filter Tank Top, 580 sq. ft. | R0357300 Style_Retro Heads They have several steel balls

They have several steel balls located inside which give the ability for movement while having a flat surface on their top side with holes meant for screws that lock them into place on the frame

it provides full coverage while reducing system stress and turbulence

they give the cleaner the ability to cover the entire surface of your pool while it sucks and pulls up dirt and debris

This body assembly is the main housing unit for both the upper components of the TR2D suction cleaner such as the engine assembly and hose connections

Jandy CV Series Cartridge Filter Tank Top, 580 sq. ft. | R0357300 Style_Retro Heads They have several steel ballsJandy CV Series Cartridge Filter Tank Top, 580 sq. ft. R0357300 This tank top is designed to use with Zodiac CV and CL series cartridge filter models CV340, CV460, CV580, CL340, CL460, CL580 and also compatible with Zodiac Jandy DEV and DEL series D. E. pool and spa filter models DEV60, DEL60. Measures 580 square feet.