The control horns mount like any other to the servo output shaft. The nice feature with SWB is they now offer a 'duel lock' feature. The arm screws down like any other, but these have a split center with two additional bolts that go through and pinch the servo output shaft. Also the holes for linkage are pre threaded for 4/40 applications.

If your question pertains to the above rigs, the servo tray comes with cut outs for mounting more than one servo. It also comes with an attached bell crank to keep the tension of the cable, under load, off the servo itself. Offered with a straight arm for parallel runs or an offset arm for crossed cable configuration. The servo arms ar ganged together with short linkage and connected to the bell crank.

Here is a pic of a single servo, JR 8411 on a 10 lb. 2 meter plane. Didn't think it would need a tray and bell crank, but it would help extend the life of the servo. I used an offset arm for a crossed wire set up and a straight arm through the rudder. Joe