These compact 400w units from maxigrow have an encapsulated choke potted in resin in an injection moulded enclosure which ensures silent running the smart ignitor is also timed to protect against lamp failure the ballast is wall mountable available with euro diamond reflectors with dual spectrum son t plus or metal halide lamps approximate maximum coverage 90 x 90cm conventional ballasts rely on simple and basic air vents in the outer case to cool and protect the internal components the