Well, that structure attached to the choke about which you asked, is part of a choke operating lever. Two parts to it; the part you asked about is a home made female 1/4" hex. At the bottom of the hole is glued one of those super strong neodemium magnets. There is a hole in the cowl that lines up with this hex-tube. Once the cowl is installed, I insert the mating part, a handle (shown in these new pics) which incorporates a piece of allen wrench stock. The magnet holds it in strongly, even during flight. It's an easy way to take the cowl on and off without a lot of hassle reattaching a choke lever.