These things go with the Tank Track 2in, Tank Track Idler Arms, Tank Track double rollers, in my things. These are all of the electronics cases and covers for the back of the tank. Use with 1/8" x 1 1/2" frame rails. Sabertooth and receiver case screw together through the receiver case. Room for wires for motor and switch under the Receiver case. Case covers, lids and Louvered motor covers finish the back of tank. Lid fits both Sabertooth case and the receiver case. Drill guides for motor rail and frame rails fit the updated gear cases and these items. 12-15-2014 Just added a perch and holder for a radio Shack 276-150 circuit board. Went with an Arduino Micro Board on a 40 pin zip socket soldered to the board with power to everything from the 7.2V battery through a 7805 regulator to power accessories, Arduino Micro gets full 7.2V. 555 timer for flashing Led's on the tank and switch for headlights on the board with plugins. Has all of the pins attached to the Micro with futaba Jr plugins on .100 strips. Makes it real easy to add new stuff to the Micro ports, power and ground are right there. Two tactile switches (doors up and doors down) under front bumper controls the shuttle bay doors through Micro to run door servo. If needed I can give some schematics of the board.Louvered motor covers are paper thin, have to build with full support and it is tough to clean out the louvers without breaking them. Will be working on some other covers. Some of these are difficult to print, all of the cases will need raft and full support. Switch case, may need support. Switch was a three terminal two position sliding switch I picked up at radio shack. Lids, Sabertooth mounting blocks, no raft or support Everything uses #4 x 3/8", 1/2" and 3/4" sheet metal screws. Drill out to .120" where the screw goes through, drill to .089" where it threads.