UAC sends in a link to their unpacking video of the UAC Module Shock Buffer for the Hi-Capa Series... "3 Different hardness (3 soft, 3 medium, 3 hard) are included in the package. It is an interchangeable design that can suit personal prefernce, from steady soft recoil to affressive fast response, short stroke.

Suitable for all plastic and metal slides.

It uses an advanced anti-oil rubber material which is superb in shock absorbing, durable and prevents swelling that can cause jamming."