Original R-Columbia Products Metal-Strobe — all-metal phonograph speed calibration disc.

Used to precisely check and adjust turntable speeds (16⅔, 33⅓, 45, 78 RPM).

Includes original paper sleeve (shows age wear) and promotional Fono-Magic insert.

✅ Made in Highwood, Illinois, USA

✅ Material: Metal (aluminum)

✅ 4-speed calibration design

✅ Condition: Very good vintage condition, sleeve shows wear from age