This is a very handy block for those time when you want to hold something that uses armature wire.
Place the armature wire into the hole and tighten the 1/4-20 screw up against the armature wire.
The armature wire will be 90 degrees perpendicular to the tube that this block is attached to.
The hole for the armature wire is .312 (5/16th) inch diameter.
Great for stop motion animation.