I have the hydra 635 , for the $ I think it's a great thermal ,haven't mounted it yet , just playing around with it as a scanner, will probably mount a on my 357 cal airgun , my only other experience with thermal is the sightmark mini wraith and the DNT is definitely a jump up from that.wish I had waited 4 months and for 300 $ more I could have got the new 650 R that has a LRF and a ballistic app built in and a 50mm lens instead of a 35mm.hoping to see some reviews on the 650r ,if they are positive and that much better than the 635 I might just get that one too