Specification: Material: stainless steel Size: height: about 8mm dimensions: 4mm / 5mm / 6mm / 8mm / 10mm / 12mm Package include: 12 x drill dowel pin(2pcs for each size) ✔Stainless steel material is strong and durable, you can use them safely. ✔ With various sizes from 4 to 12 mm, it is possible to install furniture or boats of different sizes. ✔ The centering tools are not for hard surfaces, they are mainly used for woodworking. WARM NOTE: 1. It is not suitable for children under 3 years old. 2. There may be slight chromatic aberration from pictures 3. Manual measurement, please allow slight error and double check the size before purchasing. If you are unsatisfied with our product for any reason, please feel free to contact us and we will provide you with the best service!