Pondmaster Replacement Rigid Pre-Filter for Magnetic Drive Pumps 9.5-36This Pondmaster Replacement Rigid Pre Filter fits Pond Mag (formerly Mag Drive) pump models 9. 5, 12, 18, 24, and 36. The pre filter aids in the filtration and health of your pond or water garden by preventing large debris such as sticks, twigs and large rocks from entering the pump chamber and potentially damaging the impeller. Made of durable high impact plastic Prevents impeller from being damaged by debris Easily slips on pump intake Fits