M-274 STROBOSCOPE Speed Adjuster. Published by the Michigan Antique Phonograph Society (MAPS) in the December, 2009, issue of "In The Groove". It is based on the original Caruso Stroboscope found in "Caruso On Record." HOW TO USE: Place the stroboscope on your turntable, the hole over the spindle. Illuminate it with a 60 hz bulb, such as a long work light (USA only), and adjust the speed dial until the desired speed ring seems to stand still. The speeds are indicated on the rings. Asking 50 cents WITH ANY ADDITIONAL ORDER to cover the cost of the stiff 67 pound paper, cutting and printing.