ECWCS Generation 3 Level IV Windbreaker, "New OCP," USGI/RFI Issue. 

This jacket is not insulated -- it is meant to serve as a windbreaker, on top of other insulated layers (Level 1-2-3).

Shell Layer: Designed to be worn with base and insulative levels in transitional environments to provide wind and sand protection.

The Wind Jacket is designed to act as a low volume shell layer that optimizes the moisture wicking properties of other GEN III insulative and next-to-skin layers. It is also designed to be worn under body armor. Constructed from stretchable nylon with a water resistant finish, this full-zippered jacket provides wind and sand protection with low weight and bulk.

***NOTE:  There are no Level 4 trousers.  Level 4 ECWCS is a jacket only.***

OCP has 15 NSNs, falling under LIN J05015.  MultiCam (the older pattern) is also available, under LIN LIN E95531.