The Shure M16 Studio Dynetic and M12 were introduced in March 1957 at the Institute of Radio Engineers national convention. 

The M16 was for records up to a 16" diameter; the M12 was for records up to a 12" diameter.

Either tone arm could be supplied with the Shure M1 phono cartridge - for monaural LP records.

SPECIFICATIONS:
Tracking Force: 1 gram
Frequency Response: 20 to 20,000 cps plus or minus 2 db
Sensitivity: Output at 1000 cycles-14 millivolts for 10
cms/sec
Recommended Input Impedance: 10,000 ohms
Inductance: 130 millihenrys
DC Resistance: 180 ohms
Stylus: .0007" Diamond
Needle Compliance: 7 x 10-6
Needle Tip Mass : 1.25 milligrams
DIMENSIONS:
Over-all length :
Stylus tip to center of arm base: 11" 1 8%''
Arm base diameter: 2" 2"
Range of height adjustment : 1 5/8'' 1%.
Arm pivot to turntable center : 10'95'2' 8%''
Net weight (arm and cartridge): 11.1 oz. 1 10.6 oz.

Specifications

Overall length: 374mm

Stylus to centre of base: 279mm

Base diameter: 50.8mm

Range of height adjustment: 41.3mm

Arm pivot to turntable centre: 269mm

Weight: 315g