"I use the standard master cyl
"I use the standard master cylinder lockout switch - same as I used for the drums. Small brass on/off manual valve works as well, placed in-line after master cylinder outlet(see link above). The local trailer shop sold me the master cylinder and the discs, with the valve. The only downside is that I have to get out and lock out the brakes before using reverse. Could be a pain if doing multiple forward/reverse jockeying, but the same could be said for drums. The small lockout valve allows for better jockeying, but if forgotten in the off position, the brakes will not function at all, where the electric is supposed to reset. How much trailering do you do? I keep mine on the trailer and head to the ramp to drop her in to use it and 3 years, no problems, no complaints."