The Beiter pin nocks are:
Known for their unique asymmetrical design which avoid nock pinch
Incredible precision and tight tolerances as they all come from a single mold
Are very popular amongst target archers
Sold in packs of 12
Available in size: #1 (small groove) and #2 (large groove)
 
For more details about these nocks as well as other nock options, check out or nock guide.