LiftMaster Keypad

[regression]

I have a LiftMaster garage door opener. On the opener, the part number is 41A502-1F. I "think" the model is 1255R, but I don't see that number on the opener. I just had it written down....

Anyway, I would like to purchase a keypad to allow other people (neighbors when I am out of town) to easily open my garage door. I found this on Amazon but not sure it will work:

Liftmaster 377LM 315MHz Garage Door Keypad

I don't have a "purple" learn button, but there is a red button. any idea if the above will work? I am attaching a picture of the opener (hopefully it came out ok).

Thanks.

[regression]

An update, the keypad I listed in my original post did not work. This one did:Clicker® Universal Wireless Keyless Entry System KLIK2U

[tmordoor]

Asyou know the 377LM key pad is only for operators manufactured Jan 2005 or newer!!