Combination: 20mm switch ear * 10, with 1 storage box included. Material: Made of 304 stainless steel, rust proof, not easily broken, and has a long service life. Easy installation: Adopting a quick release spring rod design, no tools are needed, just slide the switch with your fingers to quickly replace the strap. Compatibility: The ear diameter is 1.5mm, suitable for most watches that require a 20mm strap. Attention: This earphone requires a groove for installation. Please ensure that your strap has a groove that can fit this earphone. High Material：Made of 304 stainless steel. Attention: 1.please keep them away from little kids;2.If you receive a defective product or have any problems about item, Please contact us and we will assist you as soon as possible.