CAST ALUMINUM 12 - 16 Combination Field ANIMATION DISC (catalog number: S0185 - order code: 1504 - s/n: 1053)
 
Made around 1987 by Fax Company a division of Alan Gordon Enterprises, Inc. 
This company is still existing but moved completely to live-action film but at that time Alan Gordon was one of rare and leading suppliers of animation equipment.
In later years also sold by Cartoon Colour Co., Inc. under catalog No. 1413

This disc can be used for 12 field as well for 16 field by turning around the ‘MAGNABAR’ a magnetic moving pegbar however the dimensions of the opalite plexiglass window will keep the same of course: 24.3 x 29.4 cm.

One pegbar can be used because of having 4 original Acme pegs but unfortunately the second one did lost all pegs. 

No problem for the animator who wants to work on this disc by taping a separate metal pegbar on the existing one and for the collector among us it should be possible to find at least 2 original oblong pegs (catalog number: S0210 - order code: 1550) in some American closet drawer.