Warning: even by MTS's own admission, they do not work with all sockets. When the lock a socket is unlocked, the ball is loose, when you rotate it, a cam behind the ball pushes it out, locking the socket to the post. The trouble is some sockets have the detent too deep in the socket so when you try and rotate the post, the ball cannot come fully out, you cannot fully rotate and it does not lock. I have heard of people forcing them and thinking they are breaking them in but they are just breaking them. I mounted a set of HF shallow and deep impacts on a couple of them, with no problem. I bought some MTS 3/8"rails and a lot of chrome SK and Williams would not work. Some sockets have no detent at all. If they fit, they are fine but make sure they work with what you plan to put on them. They are out there in a lot of different flavors. Just looking at 1/2", MTS has a 22", 16 post that only would fit in my drawer diagonally,and I think there is a short 12 post version. In between is a Craftsman/ MTS that is 19",14 post. These all are aluminum rail, magnetic back. Then then there are cheaper MTS plastic rails with just a rubber pad on back. Then I see Torin selling the platic rail version at pretty low prices on ebay. They all use the same Lock A Socket posts. I think they are best used for heavy sockets like deep impacts that can fall off a rail with spring loaded balls in the posts. What I have settled on is the Gearwrench rails. They are ball detent, the posts are inside the rail, like lock a socket and I have never broken a post. The rails are glass re enforced nylon, but no magnetic back. They are quicker than the lock a socket, nothing falls off and they are less fussy because like a ratchet, the ball is spring loaded and works with any socket. I will get a couple of more MTS rails for my SAE impacts.
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