Hastings 3.125" Standard Bore, Single Cylinder Ring Set with 3/32" Top Ring, 3/32" Second Ring and a First Oil Ring is 3/16".
This Hastings Single Cylinder Ring Set does not specify Ring Material or Ring Surface Treatment

Application Summary:

Year Make/Model
1958-1963 American Motors American
1958-1960 American Motors Rambler
Attributes
1st Oil Groove 3/16
1st Oil Ring Material STEEL RAIL/STAINLESS EXP
2nd Groove 3/32
2nd Ring Surface Treatment PHOSPHATE
Alternate Part Number 680S
California Proposition 65 No
Engborein 3.125
Hazardous Material Code N
Life Cycle Status Code Available to Order
NAFTA Preference Criterion Code B
SDR Required Flag N
Top Groove 3/32
Top Ring Surface Treatment PHOSPHATE
GTIN 00075538036135