Will this fit my coil machine?

The threads are 8-32, the US standard used on most coil machines, so the set threads into standard post holes. Check your frame's thread size before ordering if it is imported or non-standard.

What is the difference between the top and bottom posts?

The top post is longer at .645 in and carries the contact screw .325 in from its base. The bottom post is .485 in long and has a clipcord hole .310 in from its base.

Why a copper contact screw?

Copper conducts better than brass, so the contact screw carries current with less resistance at the contact point. It tarnishes faster than brass and benefits from occasional cleaning.

How is the contact screw held in place?

A nylon-tipped set screw tightens against it. The nylon tip grips without gouging the copper threads, and the screw can be adjusted or removed later.

A top binding post, a bottom binding post, a copper contact screw and a nylon-tipped set screw.

Do the posts need maintenance?

Yes. Brass and copper oxidize, so wipe the contact points periodically to keep conductivity steady. Check the set screw's grip as the nylon tip wears.