Quality material: the adjustable glasses chain ends are made of durable silicone and iron, customized long spring combines quality stainless steel material with exquisite technology, and no need to worry about rusting and fading. Adjustable and comfortable: adjustable design can fasten the silicone loop with spring to fit for any size of glasses, move the stainless steel hoop that sliding up means lock and sliding down means unlock, necessary parts ensure the safety of your eyeglasses when moving and provide more comfortable use experience Wide usage: for any handicrafts objects that require end loops and stationary hoops, it is essential accessories for jewelry DIY enjoyment like sunglasses chain, sports eyeglasses strap, glasses necklace and so on. Size: the silicone hoop is approx. 23 mm in length, 7 mm in width, long spring is approx. 8 mm in length, universal size for most eyeglasses chains. WIDE USE:Perfect for any craft project that requires an end loop. Specification: Material: Silicone , Iron Size: 2.3x0.7cm/0.91x0.28 inch Package Includes: 50 Pieces Glasses Chain Ends Note: Please allow slightly difference due to manual measurement. Color may be slightly different since different monitor. Thanks