First, we own/operate a ranch so we have many pieces of equipment that require lubrication (greasing). Most have at least one fitting that is hard to access and often results in a mess because the coupler won't attach securely. The worst is a snocat we have that has 26 grease fittings on the axles and drive train. None of these are easy to access and most are "blind". I had hoped that this lock-on coupler would help decrease the amount of grease not going in the fitting and make securing the coupler a bit easier. I just serviced the snocat and this is what I found: 1) this fitting is larger than a standard coupler, both in length and diameter, and will not work in areas with limited clearance; The handle release adds to this issue; the handle release has a pretty stiff spring, so if your hands are greasy and clearance is limited, it is virtually impossible to hold it open and get the coupler onto the zerk fitting; though the coupler "locks" onto the fitting; if you are working on a "blind" fitting, the face of the coupler is flat, which won't allow you to feel if you have it over the fitting and the jaws are too stiff to hold open for very long; if it is not on absolutely straight it will leak grease; without a hose swivel (which LockNLube markets, not surprisingly) you will find yourself twisting your grease gun every which way trying to get the coupler open, and sometimes, loose because of the large spring handle. After struggling with it 26 times yesterday I ended up going back to a strong 4-jaw "standard" coupler. I'll keep it as sometime I might find a use, but overall, it didn't work at all for me.