1. Frequency: Check the back of your remote to make sure the frequency of the remote is 390mhz (megahertz) or says liftmaster, chamberlain, or sears craftsman. All of these use the same frequency of 390mhz.2. Dip switches: Open the battery compartment on your old garage door remote and look to see how many dip switches (tiny switches in a row) it has. If your old remote had 9 dip switches, then it's a match for this remote. If you don't have your old garage door remote, you can also look to see how many dip switches are on the back of your garage door opener (the overhead unit in your garage). The number of dip switches on the back of the opener is the same as on the remote.
This 61lm lift master remote uses 9 trinary dip switches to set the code
390 MHZ Frequency, works on models from 1984-1992
Also compatible with wireless keypad model number 66LM (same as model 740CB, 139.53776, 139.53876)
12V battery and visor clip included