These are made of following type of different material:
| Catalogue No. | Size(DIA) |
| SSI-PHY-MECH-18.1 | Aluminum 13mm |
| SSI-PHY-MECH-18.2 | Lead 13mm |
| SSI-PHY-MECH-18.3 | Brass 13mm |
| SSI-PHY-MECH-18.4 | Copper 13mm |
| SSI-PHY-MECH-18.5 | Iron 13mm |
| SSI-PHY-MECH-18.6 | Zinc 13mm |
| SSI-PHY-MECH-18.7 | Aluminum 19mm |
| SSI-PHY-MECH-18.8 | Lead 19mm |
| SSI-PHY-MECH-18.9 | Brass 19mm |
| SSI-PHY-MECH-18.10 | Copper 19mm |
| SSI-PHY-MECH-18.11 | Iron 19mm |
| SSI-PHY-MECH-18.12 | Zinc 19mm |
| SSI-PHY-MECH-18.13 | Aluminum 25mm |
| SSI-PHY-MECH-18.14 | Lead 25mm |
| SSI-PHY-MECH-18.15 | Brass 25mm |
| SSI-PHY-MECH-18.16 | Copper 25mm |
| SSI-PHY-MECH-18.17 | Iron 25mm |
| SSI-PHY-MECH-18.18 | Zinc 25mm |
Can be supplied individually or as set