Hi all, I want to buy the correct type/size of socket to be able to remove the bolts holding down the inlet manifold on my Mike Huddart built SBC. Could someone please confirm what type of bolt heads these are? I have googled bolt heads and I am fairly sure they are referred to as 12 point bolts, but the guy in Halfords had never heard of one, which don’t mean a lot I know

One of my old 3/8” ring spanners seems to be the closest fit, but is a bit sloppy and I don’t want to round of the bolt head.

Apart from allowing a greater range of spanner positions, why are these are sort of bolts used, because they look more prone to rounding off than the normal hex bolts.