Key Features to Consider When Buying an A/V Receiver By Will Greenwald on Aug. 9, 2010 at 11 a.m.. A/V receivers are vital components in any home theater. They're also huge beasts with many, many different features, and it can be confusing keeping them all straight. Jul 31, 2008 · Here is a close up of the heads. It has a fixed head on the right and the center head have a blunt point and a sharp point. The points for marking and the blunt points for a fixed point hole or in an ellipse engine. The head on the left holds stubs of pencils in it for laying out circles, arcs and ellipses.