Rebuildable: Oversized BIGBearing is easily replaced with our solid steel billet design Seamless: Seamless pulleys are much easier on belts Time Cutter ZX Series: Z17-44 74401 (SN220000001-240999999) 74502 (SN230000001-230999999), 17K-44ZX 74601 (SN230000001-230999999), 18-44ZX 74602 (SN240000001-240999999), 18-52ZX 74405 74702 74405FR (SN240000001-240999999), 19-52ZX 74802 (SN240000001-240999999), TITAN HD 1500 Series 74450 74451 74452 74453 74454 74460 74462 74465 74467 78450 (SN400000000-999999999), TITAN HD 2000 Series74461 74466 76601 76602 (SN400000000-999999999) Z Master Models: Z147 74161 (SN240000001-240999999) 74170 (SN200000001-2000999999) 74176 (SN210000001-230999999) 74270 (SN200000001-210999999) 74161TE (SN240000001-240999999), Z148 74162 (SN240000001-240999999) 74199 (SN230000001-230999999), Z149 74411 (SN250000001-260999999), Z150 74164 (SN240000001-240999999) 74171 (SN200000001-2000999999) 74177 (SN210000001-230999999), ZX440 74406 (SN250000001-280999999) 74603 (SN260000001-280999999), ZX525 74407 74806 (SN250000001-270999999) Z Master Professional 2000 Series 74490 74491 74492 74495 74496 77248 77260 77280 77282 77284 77287 77293 77299 (SN400000000-999999999), MyRide 2000 Series 74493 74494 74497 77290 (SN400000000-999999999) HD BIGBearing Billet Idler Pulleys are machined from a single piece of solid steel and use a Larger Replaceable Pulley Bearing. Seamless Billet Pulleys provide superior durability, precision, and increased belt life. We use a larger bearing to increase life; and our billet pulley design makes it possible to replace the bearing if it fails. Designed specifically for heavy-duty applications, these pulleys offer the absolute best replacement option.