The Great Planes version of those little critters are called "screw-lock pushrod connectors" and the main body is brass and square in cross section. It uses a socket head cap screw (allen wrench bolt) to squeeze down on the pushrod wire to secure it. I only use this type on throttle pushrods as I am one of those that don't trust them for control surface use. I always put a drop or two of Loctite on the screw and have not had any problum. Be aware that if the pushrod wire is too thin the head of the allen screw will bottom against the top surface of the connector before clamping the pushrod wire. I like them for throttle use as it is easy to adjust the linkage to the carb. The Great Planes version of other type that has a 90 degree bend in the wire going thru the nylon keeper that then snaps onto the pushrod wire are called "faslink pushrod keeper" by G.P. I use these without problums on control surfaces of small to medium size (40-60) sport and scale planes. I do add a small piece of fuel line as a safety retainer as is common practice on regular clevis instalations. John Buckner is correct that this type can interfere with the servo arm when used in an inboard arm hole so be aware and notch the keeper if needed. On large 1/4 scale or fast high load applications I like metal threaded or soldered clevis connections or pull-pull cables. Andrewskj, there many different ways to build and outfit these things and with experience everyone finds techniques and parts that work for them.