Another upgrade items for hi-capa fans from X-Fire/PDI-Japan... "It is subjected to surface treatment 'QPQ' that is valued by SIG, and has thrust ring. This product has polished shaft-surface and is subjected to surface treatment 'QPQ' to reduce the friction resistance when blowback. QPQ has higher durability, fatigue endurance, and corrosion resistance than hard chrome plating.

This surface treatment has effect of surface-hardening and rust prevention, and is subjected to also SIG's slide. At engine, it is used to crank shaft and cam shaft.

This product consist of 2 parts that CNC all machined. They are press-fit by the pressure of one ton or more, and is laser-welded.So it has superior durability.

Thrust Ring acts as a bearing.

Thrust ring is made of delrin because here is a place of contact between the spring and the ring. It reduces the burden, and it does not lodge.
When ring wears thin, all you have to do is exchange it. The cost is lower than exchanging the bearing.

When you set an ring, slide stroke shortens by about 1.5mm. In case of original one, it does not become short stroke. If you customize that, it may become short stroke. in that case, please put out the ring."