Hach DR300 pocket colorimeter, chlorine (free + total). Colorimetric photometry using Hach DPD reagents. Range 0.02-2.0 mg/L Cl₂ (low range) and 0.1-8.0 mg/L (high range). Battery-powered, IP67. Applications: drinking water disinfection verification, cooling-tower chlorine monitoring, ballast-water TRO verification (see our Techcross ECS BWMS spare parts reference). Ships with DPD reagent starter pack; refill packs of 100 tests stocked.