The NS6 and NS4 Series is designed specifically for use with HOCHIKI Conventional Models SIJ-24 Ionization Smoke Detector, SLR-24V Photoelectric Smoke Detector, SLV-24, SLV-24N, SLV-24V Photoelectric Smoke Detectors. SLR-24H Photoelectric with Heat Smoke Detector. SLR-835 Photoelectric Smoke Detector, SLR-835H Photelectric Smoke Detector w/heat, or DCD-135/190 Fixed Temperature/Rate-of-Rise Heat Detector. The Base is an electronics free 6" base featuring a plastic tamper-lock lug. Each base is equipped with a resistor. Refer to the chart (left) for additional specifications. TThe NS4 base is a 4" version of the NS6 base.