Kromasil HPLC Guard Cartridges Kromasil 100-3.5-C18 10-21.2 mm, 3 pc/PAK

A cartridge: This is the expendable column packed with the same packing as the HPLC column the user intends to protect. It's 1 cm long. Cartridges are sold in 5 and 3 pack for analytical and semi-preparative columns, respectively.