Factory Ruger OEM Parts. 

Included parts:

MKIV Firing Pin

Rebound Spring Support

Firing Pin Spring

Extractor Plunger

Extractor Plunger Spring

Guide Rod Assembly

Fits all Ruger MK series (MKII, MKIII, MKIV) including all 22/45 models.  Replace old or worn out parts with these brand new parts or ideal kit to have for spare parts.