SunMaster Cool 400W is a vegetative-stage metal halide grow bulb engineered for blue-leaning output. On SunMaster’s official Cool table, the 400 W model is rated 5,500 K with a total photon flux of 480 µmol and 430 µmol in the 400–700 nm PAR band, and a 15,000‑hour rated life in a universal burn position. The bulb runs on a mogul-base (E39/E40) HID system and is compatible with standard M59 ballasts. In typical reflectors it covers roughly a 1 m × 1 m footprint during veg, making it suitable for clones, seedlings, and maintaining mother plants. Pairing a Cool lamp for growth with a Super HPS for bloom is a common SunMaster workflow to maintain compact structure early while preparing dense canopies for flowering.
