Abstract: A spin-on filter unit for filtering liquids which may be readily disassembled and which utilizes a perforated center tube support disposed within a housing canister having both an open end and a closed end, a mounting head assembly which includes a bayonet connector mechanism adapted for releasable engagement with the open end of the housing canister, and a spring mechanism mechanism which acts upon the center support tube to urge the mounting head assembly bayonet connection mechanism into releasable engagement with the open end of the housing canister after rotation of the mounting head assembly about its center axis relative to the housing canister.