30 sq. ft. Cartridge Filter Intex 58621, Krystal Klear Models 520/530, Sand-n-Sun, Wet Set, East Set C-5330 FC-3748 Diameter…………………………………5-3/4" Length……………………………………12" Top End Cap: id/config……………..1-7/8" / open Bottom End Cap: id/config…………1-7/8" / open The cartridge is used on: Intex Recreation Krystal Klear Model 520, Krystal Klear Model 530, Intex 58621, OEM P/N 58601 Krystal Klear Model 520, Krystal Klear Model 530, Intex 58621, OEM P/N 59901 Krystal Klear Model 520, Krystal Klear Model 530, Intex 58621, OEM P/N 5F17 The Wet Set Model 520/530, Type "D" ,Note: OEM has two Type "D" filter cartridges; Verify OAL to identify the correct Unicel replacement