These are Triplett Model 220-6
DC Current Micro-amp Deviation Analog Panel Meter +50uA / -50uA
(marked in DC Microamperes

Meter Face: 2.77 inch wide x 2.40 inch tall
Panel thickness: 0.44 inch
Body depth (behind panel): 1.42 inch
Mounting stud length:0.56 inch
Overall depth with terminal posts: 2.13 inch