The Merlin Garage door openers don't say the bulb type you need. If anyone else needs the bulb go to SuperCheapAuto or Repco. It's a BA15s bulb, which repco calls the R241BLL (that's a 1). $7.29 for two at Repco today, or $4.79 for two at SCA. Fitted and it works fine.

 

Important note: 24V 21W, not 12V. 12V bulbs will blow.