Viega 78177 ProPress coupling No stop Smart Connect technology Copper, 3/4'' x 3/4''

The Viega 78177 is a 3/4 inch copper ProPress coupling built without an internal tube stop, so copper tube can slide all the way through it. That is what you want for repairs and tie-ins where neither pipe end can be moved: cut out the damaged section, slide the coupling fully onto one end, bring the new piece in line, then slide it back to center and press both sides. A stop-type coupling butts each tube against a shoulder, which is fine for new runs where you can spring the pipe apart, but useless on a fixed repair. The tradeoff with a no-stop is that you have to mark your insertion depth yourself, since nothing inside the fitting sets it for you.

Yes. The 78177 is sized 3/4 inch by 3/4 inch and takes standard 3/4 inch nominal copper tube on both ends, which covers type K, L and M since all three share the same outside diameter. Press fittings seal on the OD, so the wall thickness of the tube does not change the fit.

Smart Connect is Viega's unpressed-connection feature. If a joint gets missed during pressing, water leaks past it noticeably at low pressure during the system test, so the installer finds it before the walls close up rather than after. The 78177 coupling carries that feature. It does not replace pressing, it just makes an unpressed joint obvious.

The coupling ships as the fitting with its sealing element in place, and it presses with a ProPress tool and the correct 3/4 inch jaw or ring. Beyond that you need a proper square cut, the burrs reamed off inside and out, and the tube marked to your insertion depth on each side, which matters more here because the no-stop body gives you no internal reference. No solder, flux or torch involved.

Yes, it is manufactured in the USA, which matters on public and institutional jobs carrying domestic-sourcing requirements. Body material is copper.

No. The 78177 is a copper press coupling with press ends on both sides, and it is made to join copper tube to copper tube. PEX needs its own PureFlow-style press system, and iron or steel pipe needs a different fitting family entirely. Mixing systems at a press joint is not something the sealing element is made for.

The fitting body itself measures 2.008 inches across its longest dimension with 1.248 inch height and length figures, so it is compact. The clearance that actually governs you is the press jaw swing, not the coupling, and a slip-type no-stop coupling also needs enough straight pipe to slide the body fully clear of the joint before you recenter it. Tight ceiling cavities and pipe close to joists are where installers run out of room.

Each one weighs 0.131 lbs, so a handful adds almost nothing to the bag. For maintenance techs stocking a van for copper repairs, the no-stop version is the one worth carrying in quantity, since it handles the in-line repairs where you cannot separate the pipe ends.