The Tonar Tone Arm Alignment Gauge is a nifty product that is a multiple of gauges in one. You can check and confirm tone arm geometry plus pivot distance, effective tone arm length, overhang and azimuth.
Tonar Tone Arm Alignment Gauge Features;
Mirror for checking azimuth
Overhang gauge
Offset angle gauge
Tonearm alignment gauge
Measure distance from platter centre to horizontal arm pivot