This is a mechanical cap that resembles ZPI products. I mistakenly bought this when I was buying up ZPI products. This type of ZPI mechanical is quite rare and often expensive, so please consider purchasing if you don't mind. [This is NOT a ZPI product.] Please check the photos. Compatible with mechanical caps for 21 Zillion and Steez A2 types. As this is a used item, please no claims and no returns.