Solid brass eyelets  and rings.
Sizes are  
pp 18 or 5.16 mm or 13/64"
pp 20 or 6.75 mm or 17/64"
pp 22 or 7.94 mm or 5/16"
pp 24 or 9.53 mm or 3/8"
pp 26 or 11.11 mm or 7/16"