The Vinyl Source 
 
For sale, a high precision arc protractor for cartridge alignment.
This protractor is made of 3mm High Glossy Black Acrylic Perspex, high-precision laser cut and engraved.
The arc protractor is the most accurate protractors for cartridge alignment; this one is designed for the following Audiocraft/Ultracraft tonearms:
AC-300MkII
AC-3000
AC-3300
AC-30
AC-33
AC-300
AC-300C
The geometric features are compliant with Audiocraft/Ultracraft specifications; see the first picture.
 
It is supplied with detailed instructions.
We also make custom protractors to the client's specifications.