Exact strip DPD-3 combined chlorine (481648) offers a safe and convenient delivery system for your DPD testing. Must be used in conjunction with exact strip DPD-1 free chlorine for combined/total chlorine testing. There are no more tablets to crush, powders to spill, or dispensers that release irritating dust. All reagents, as identified in the AWWA handbook (4500-including G. ), are delivered from the exact strip pads. Can be used with most 10 ml DPD combined/total chlorine photometer systems.