Harken Small SS Stand-Up SpringWeight - .13oz (3.7g.)
Stand-up bases allow a wide variety of blocks to be held upright, swivel freely, and pivot for fairleads under load. Springs are used to support blocks on padeyes, eyestraps, bases and traveler cars. Keeps blocks from hitting the deck.
A - 1in (25mm)
B - 3/4in (19mm)