VEVOR Pool Filter Cartridge, 4x 130 Sq. Ft, Spa Hot Tub Filter Cartridge Replacement, Compatible with Pentair CCP520, R173578, PCC130, Secure for Kids & Pet, Trilobal Pleated, Easy to Clean

The 4-piece pool filter set (525 sqft²) is a replacement filter for the GL520. For the GL420, you should choose the accessory canister pool filter set (4-piece, 425 sqft²).