Oldcastle Heavy-Duty Butterfly Hinge, Black, 2 pc.

Super strong hinges for a large gate. We needed something narrow to mount to a 2 x 4 and these did the job

Bottom line up front: this is a serious, heavy set of hinges, but it's not for casual do-it-yourselfers. The springs inside these hinges (they're self-closing) are very strong and just about impossible for one person to hold open in a position which allows the person to screw the hinge fast to the gate or gatepost. Also, the hinges are meant to be installed on a very flush, trim, level gate with level, flush posts. I was trying to install them on a garden gate I built myself from construction lumber and a heavy wire hog panel, and install the gate on pressure-treated posts in my garden fence. The posts aren't level or even because the ground isn't level (it's on a slight slope), so this was a hinge too far. I ended up using simpler gate hinges from a local hardware store, and will save these hinges for a more sophisticated project. Again, the hinges themselves are a first-class piece of gear, but they weren't what I should have been trying to install on my garden gate.