Ready-Link® Rack (V4) Base. The free standing rack system is designed for infield assembly for indoor and outdoor installations. Designed to work with NPE, NPE-2, NPN, NCB-E, NCB-H, NFC, NFC-H, NHB, NFB, NFB-H, NHB-H, NHW-A series units. Base rack allows installation for up to 2 units back to back.