LEORX Metal Sliding Bar Tri-glides Wire-formed Roller Pin Buckles Slider Strap Adjuster 25mm Pack of 20 Pack of 20pcs roller pin buckles, which is made of durable iron material. Color: Silver. Material: Iron. Inside dimension: 25 * 19.5mm. Great for hundreds of uses collars, belts, backpacks and much more. Fit for 25mm webbing, also can be used in various applications such as sports equipment, pet products and so on.