TN 609971 Panel Air Filter Pre-Filter for Nobles and Tennant 3620, S8, & Scout 28 Battery Sweepers. This pre-filter assembly fits panel air filter model TN 607586. Found on Tennant 3620 and S8 sweepers and Nobles SWP-2800, Scout 28 sweepers. One pre-filter required per unit. Priced Each. Replaces Nobles, Tennant 609971. Our Part Number TN 609971