If your Garage Door Opener is a 1/2hp or 1/3hp CHAIN DRIVE model with a production date of 1984 to present this gear shaft will be compatible. Production date will be located on the back of the operator motor head. Get your Garage Door Opener in gear with this cost effective repair option. Fits these LiftMaster Models: 985 1240 1240R 1245 1245R 1245LK 1250 1255 1255R 1260 1260LK 1265 215WD 220WD 315WD 320WD 1345 2245 2255 2265 2565 3245 3255 3265. Do not use for openers with dual sprockets on the output shaft. Compatible with Chamberlain Garage Door Opener part number 81B0045, also compatible with the 41C4220A gear and sprocket assembly and the 41A2817 drive gear with pins repair kit. Fits these Chamberlain Models: 1100 1200 2100 2200 4100 4200 CG40 CG40D CG42D PD100 PD200 PD210 PD210D PD212 PD212D PD600 PD610 PD610D PD612KLD PD612K 5100 6200 7200 7220 7320 7420 7520D 4893OD HD200D. Do not use for openers with dual sprockets on the output shaft. Chamberlain replacement number 081B0045 Note: Also fits openers labeled under various names such as: Sears Craftsman True Value Master Mechanic and some units from Wayne Dalton. LiftMaster also "private labeled" openers for regional suppliers and dealers - usually it is very easy to see that it is a LiftMaster opener with a different name on the cover. Compare your parts to the picture above. The Large Gear is 2 3/4" x 1/2" wide with a 1/2" bore. The worm gear is 1 1/8" OD and the teeth are 1 1/4" wide (all sizes are approximate). If you have a BELT DRIVE model: The 41A4885-2 belt drive gear kit has 9 cog sprocket, the 41A4885-5 belt drive gear kit has a 14 cog sprocket. These kits are also available for purchase.