Cx interrupter levers are cyclocross interrupter levers. (EDIT) I just saw them listed as "top mount levers" as well.(EDIT) They are used as a second brake lever close in to the stem on cyclocross bikes.
If you use them you'll need to fudge how the cable and housing fit the levers since techincally you'll be using this style of lever "backwards". Because of this the cable end does not fit into a nice pivoting stop block and the cable will be bent right at the end. Because of this you will want to set them up with a short throw to limit the bending arc. Even then check them often for the first sign of fraying at the cable end just where the cable meets the molded metal. There was a thread here about a year or so back where a guy was using this style of lever and not checking and replacing the cable often enough and it snapped on him right at the end thimble because of this constant loaded bending. He was lucky and got away without any incident but it but it's obviously not a good thing. Not having the pivoting cable stop in the lever was the cause of this. By limiting the bending arc you'll get more life from the cable but make no mistake, it's living on borrowed time. There's a VERY good reason why all the end of the line brake levers allow the cable end to pivot.
What we really need is a TT lever with the proper setup for this style of cable and housing direction that clamps on rather than fits into the end of the bar. That way you leave the hole open for the barcon/barend (the same thing) shifters.
Another option I've seen done is to set up some sort of stub bars at the stem to take the place of the aero bars where the barcons normally mount. If done in a tidy manner they can look decent. But I don't know of such a product so some imagination and bodging something together to accomplish this may be required.
Last edited by BCRider; 10-23-09 at 12:05 PM.