Light weight, rounded brass with protective inner liner keeps arrow-to-string position consistent. 4 per pkt.
Blue: Suit 6-8 stand strings (Most recurve bows using small groove arrow nocks.)
Black: Suit 12-14 strand strings (The most popular size for compound bows and recurve bows using standard size nocks.)
Red: Suit 16-18 strand strings. (Suit the thickest of bow strings.)