I apologize, its an Apex XD38A (its still brand new to me). When I was comparing, I looked at the XD38/XD50 and found they were very similar. The 50 is a step up for sure, but I saved a grand and got the 38. This is the first one I have owned, but was introduced to a wide range of thermals from a good buddy who is in the business of selling them now. Got to test a couple in each price range, up to 20k. Don't get me wrong, if you have that kind of money to spend, there are much better products out there than the XD series by Apex. I think the Apex is a great buy for the price, the XD38 and the XD50.
Did I mention I love having a thermal?