HANNA INSTRUMENTS - HI771-25 UHR CHLORINE REAGENTS CHECKER Hanna Instruments Sale! from 1200 /per Qty. Add to Cart This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. Replacement Reagents for the Hanna Checker HI 771 Hanna Instruments HI771-25 UHR Chlorine Reagents Checker - 25 pack