John would like to know: Can I use the GTO-FM136 with the Apollo 633 Gate controller? Will it work with the 635? If so, I think it would work with the 633. If it will work with the 633 controller, how do I wire it to the controller? Answer: Yes John, you may either purchase a GTO-Pro Receiver or you can hard-wire it directly to the “open” input on your 633 board per the instructions outlined on the operators installation manual. Have questions regarding our products? Our technical sales and support team is standing by if needed, just give us a call at 1-800-730-8382 or contact us by e-mail as we are eager to assist you for all your access control equipment needs. Find the access control product you’re looking for today.