This is a genuine Acutex International "Almost-Perfect" M312III STR replacement stylus for 16, 33 & 45rpm, not for 78rpm. This needle can also be used in the M315IIISTR & M320IIISTR since the needles for these two models are no longer available.
Stylus tip: Bonded "shibata" line contact diamond.
"Tri-Pole Induced Magnetic System" (MM, moving magnet)
20Hz - 35kHz
Minimum 30dB at 1 kHz.
Within 1dB at 1 kHz
24 x 10-6 cm./dyne at 100 Hz
Tracking Force Range:
0.9 to 1.9 grams
29 mm. x 18 mm. x 16 mm
6.2 grams (with needle installed)
"All the Acutex pickups used a propriety variant of the MM system the company called "Tri-Induced Magnet System", it's unclear what difference, if any, was/is between this system and a normal MM but the company claimed the best channel separation in the business. The range started with the M110E that featured a simple "line contact" stylus (actually a elliptical variant), slightly more expensive was the M210 IIE and the M310 IIE, those 2 had an elliptical stylii and all three above carts had the same frequency range or 20Hz to 22KHz. The updated M310 IIIE model does not appear to have replaced the IIE model in the catalogue but rather augmented it, it uses the same stylus as the IIE but has an improved frequency response of 20Hz to 25KHz. The top range of pickps from the company all featured Shibata STR line contact stylii, the cheapest one was the M312 IIISTR, then came the M315 IIISTR that had a quoted frequency range of 20Hz to 40KHz but I have not been able to find the specs for the top of the line M320 IIISTR model."