I'm looking to pick up a compression tester to use with chain saws and hopefully other small engines. The one available at Baileys indicates that the check valve is at the end of the hose. I assuming other compression testers have a check valve(Shrader) either at the end of the hose or at the inlet to the gauge. Anywhere other than at the end of the hose will add to the volume of the cylinder and will take more pulls to get full pressure, but I don't think it matters where the check valve is, as long as there is one. Just checking to see if they all have one since I don't see them mentioned on some other testers such an Actron CP7826 which seems widely available at a lower price than the Baileys tester.