It's likely a Bomar hatch. I'd contact GW and see if they can tell you the specific details. They prob use the same one on other models as well.. Bomar is a Pompanette company.
Found a serial number when you open the hatch all the way. Contacted Bomar with the SN and It's Bomar N1086-10PX.
Can buy it directly from Bomar for $1004.00 with 5-6 wk lead time or order from their retailer, Defender for $686. But, Defender is out of stock and doesn't know when/if they'll order more