The Ronstan Series 15 Ball Bearing Triple Block is a tiny, light, and versatile block with a 5/8" diameter sheave and a very high breaking load.
Ronstan's Series 15 Ball Bearing Utility Blocks are the tiniest ball bearing blocks anywhere, running on sheaves only 5/8" (15 mm) in diameter.
They're so light, strong and inexpensive that you can use them in lots of creative applications, like shock cord retractors for your control lines, purchase systems for your foiling Moth, or outfitting your kid's El Toro, Sabot, or Opti. Use them for cunninghams, vangs and tweakers, or even for non-boating applications.