I have about twenty Protoco individual socket rails. They are wonderful, in that they're longer than most of the others I've seen recently. They therefore hold more sockets. The holes in the rails are all the same size, but the pegs are different sized on top, for 1/4, 3/8, and 1/2 sockets. The pegs can be poked into the available holes spaced as needed for the various sized sockets--including mixing socket drives on the same rail. They attach to the box drawer with double-sided sticky tape; although I rarely pulled the backing paper off the tape.
In short, they're well-designed to conserve space and maximize socket density; they hold a lot of sockets per rail.
Price varies considerably--from about $9 to $15 per rail depending on supplier. Snappy is selling them for about $12 each.
Now the bad news: They were re-designed several years ago. The older ones had round pegs of 1/4, 3/8 and 1/2 diameter. The pegs could be stacked if needed to hold tall sockets securely, yet the socket could be pulled off the rail with near-zero friction. The new design uses non-stackable plastic spring-clips which are annoyingly tight on the sockets. I seem to pull the socket and the clip out of the socket rail as often as pulling the socket off the spring clip. I wish they'd go back to the round pegs.
Second problem: The plastic rails are not overly-durable. I've had many plastic rails crack at the peg holes. Note that most of my rails are old enough to smoke--although I've got a couple of rails with minor cracks as new as 2005.
I sent an e-mail through the Protoco web site asking about pegs vs. spring clips, and warranty on the rails, but being the week-end, they haven't responded yet. I'll see how things turn out.
http://www.protoco.com/Products/Products-Socket-Organizers.htm
I'm looking at those Westling aluminum rails...but in the end I think I'm gonna get a sheet of pegboard and some wood dowels sized to poke into the pegboard.