The Interlux Dual Arc bulbs run on HPS ballasts. Consisting of both MH and HPS arc tubes, these bulbs provide a wider color spectrum in both blue & red range. Standard E39 base. 1 year warranty. The Interlux Dual Arc bulbs run on HPS ballasts. Consisting of both MH and HPS arc tubes, these bulbs provide a wider color spectrum in both blue & red range. Standard E39 base. 1 year warranty.