Urban Kixx, the short answer is "I don't know" and that's probably why you haven't heard back from others. There are caps at the Inspire where the X5S or R mounts, one on the Inspire side; one on the X5 gimbal side and there are no markings speaking to size. It's obviously DJI proprietary, so you wouldn't find them anywhere else to my knowledge. The next cap would be the camera body cap. Again, no markings, but it's a standard 4/3 mount cap you'd find on the DJI, Olympus and others lenses. You'd have one on the camera body and one rear cap on the lens. Finally, the front lens cap and that's 46mm.
Malli35998, I don't have the receipt handy to give you a date, but it is the current model and is in Like New condition (means you can't tell it has ever been used). FYI, it has a buyer planning to complete the purchase on Monday. He has first right of refusal on Monday and one other ahead of you. Expect it to be sold on Monday.
Malli35998, just fyi, when I have a piece of gear I'm not using and want to sell, my assistant and I search the Internet for any new and used prices published, then price my item very competitively. My gear is fastidiously cared for and rarely below EC, EC+ or LN condition and that figures into my price. I'm a commercial photographer and upgrade equipment often, so my unused items are perfect for someone wanting to save some money over new prices.