BULLEYE, BOXWOOD 2.5mm 24/pack
These round, grooved blocks function like a deadeye except there is only one hole through the center. They are also used as fairleads. You can make a bullseye from a deadeye by reaming out the 3 center holes into a single hole.
Bulleyes / Boxwood / 3/32" / 2.5mm / 24/pack