Interfit Flash Meter INT410 The INT410 Flashmeter offers great value for your money. Simply connect to your flashgun or flash head via the PC cord & it can be used to measure incident (from the subject) & reflected (from the camera) light in one-third increments with an aperture range of f 2 to f 32 at ISO 100. Utilises a single 9V MN1604 Battery (not included).