These are a direct replacement for the original steel retainers on:
ZXR 750 / ZX7R H1/H2 from 1989 and 1990
 
16 Retainers made of best grade titanium - Grade 5.

The original retainers weight 7,9g and the titanium retainers weight 4,8g, 40% lighter.

These retainers have a smaller profile/height (less 0,5mm) to allow for more valve lift without contact with oil seal and without requiring valve guide modifications.

Using lightweight titanium retainers allows for more aggressive camshaft profiles (lift and duration) without losing control of the valve and increased rpm limits - a must for any performance / race engine.