E-Z Clip Series Fitting, 7/8-14 Female O-Ring (Short Pilot), -12 Hose, Straight

Lubricating the nipple is not a step you want to skip. A generous coat of the refrigeration or A/C system's compressor oil needs to go on the nipple before insertion. That oil is what makes it physically possible to seat the nipple without forcing it and risking hose damage. Once it's in, there should be zero gap between the hose end and the shoulder on the nipple. If you see any gap, it's not seated right.

That's right, the E-Z Clip components shouldn't be reused according to the manufacturer.

Fit check comes down to the ends and sizes: this is an E-Z Clip straight fitting for a -12 hose with a 7/8-14 female O-ring (short pilot) connection on one end, and the other end is the line/hose/tube side. It’s identified as Aeroquip E-Z Clip (catalog C1EY82) and includes seal part 1F40106-12.

Short pilot refers to the length of the nose on the female O-ring side, and it does affect fitment in tight installations where clearance is limited. For the hose side, what matters is that you're working with -12 hose. That's what this fitting is built around, and as long as your hose matches that size, the short pilot designation is mostly relevant to how it seats against the mating port, not to the hose connection itself.