Doing old work with 12 AWG cable makes finding large enough boxes tricky. I have seen some appealing metal boxes, but I am wiring using NM cable (Romex), which needs cable clamps where it enters a metal box. I can't find these anywhere!
Some metal boxes come with them, but those are generally single-gang boxes of less than 17 cu.in., which is not enough for me. Several different attempts at searching Home Depot and Lowes' sites turned up plenty of conduit clamps (the ones like a strap with a U in it where you screw down the flat part with the conduit under the U), but no, zero, absolutely none of the two-part NM cable clamps with locknut on the inside that I needed. I found a couple huge ones (1-1/2 in, 2 in) from Halex, but none fitting the 1/2-in knockouts that are all I need.
Is there some secret place where all the cool kids buy their workaday electrical supplies that I should know about? Some magic name that I need to use to look it up? I just need bog-standard utilitarian cable clamps, not 200 options for decorator cover plates, but the latter is what the Web seems to want to sell me.
Alternatively, is there some other legit way I could protect NM cable entering a metal box that would avoid the need for this amazingly hard-to-find part?