Things I liked: Can be used for filling 3000psi Paintball HPA tanks without the need to purchase additional fittings.
Things I would have changed: Better instructions: The pump came with minimal instructions. No mention if this pump is capable of continuous use, or if you must only pump for 5 minutes then rest for 15.(I am assuming the latter, just to be safe.) And a couple minor things... The bleed screw, although fully functional, takes several turns to open completely. A bleed valve that opened with a 1/4 turn would be a nice luxury. An intake filter with a replaceable paper element for use in dusty conditions would also be a nice addition.
What others should know: I cannot comment on how this pump works with the Benjamin Discovery, as it was purchased for the express purpose of filling 48/3000 Paintball tanks, which it seems to work well for. When filling a 48/3000 HPA tank, 5 minutes of paced pumping will give around 250psi increase.(will vary with tank size) The product description states that it has a "Moisture filter", but it appears to only allow the moisture to condense in the base and then be expelled when the bleed valve is opened.(There may be some sort of internal filter, but I have no intention of disassembling it to find out.) I have used this pump to fill 4 tanks a total of about 8 times over a 2 week period with no failures of any sort. In summing up, I would recommend that it not be used in dusty conditions, but for the price it seems like a well built pump.