I originally had them mounted with the single screw in the paw to a single t slot aluminum rail. I changed my design where I have two rails held the correct distance apart with small pieces of rail. It allows me to hang the lights by putting 4 machine screws into the light itself and the head of the screws slide into the two rails. Here is a picture that shows the rail from the side and is a little easier to see how I did it.What is thay you mounted them to?