SULLIVAN MEDIUM CONTROL ROD CLAMPS S533 These are medium control rod clamps from Sullivan. These secure control rods in flying models. These are used to secure control rods to solid portions of model. FEATURES: Spring steel construction, Black finish. INCLUDES: Six control rod clamps, six 2-56 clamping screws REQUIRES: Six #4 or 4-40 screws to attach to rib or bulkhead. COMMENTS: Will fit Sullivan #503, 504, 505, 506, 511,519, 580 and 581 Gold-N-Rods as well as most other brands.