High quality solid brass O-ring. Sizes available represent inner diameter of O-ring.
Additional info and other dimensions:
Inside Diameter Wire Thickness Outside Diameter
1/2" 2.9mm 3/4"
5/8" 3.1mm 7/8"
3/4" 3.3mm 1-1/16"
1" 4.5mm 1-3/8"
1.25" 4.6mm 1-7/16"
1.5" 5.8mm 2"