1Waterproof rings are available in various sizes to meet your different needs, suitable for different watch models. 2Covers the gaps between the strap and the movement, making the watch waterproof, wonderful watch repairing parts. 3Made of high quality plastic material, long service life, durable and practical, not easy to damage. 4Professional watch maintenance tools, watch repairing and DIY watchmaker excellent accessories. 5ORing back gasket kit, wonderful replacement for the old and broken one, directly fitment.