Foxpro recommends the use of their rechargeable batteries to power Foxpro digital game calls for optimum performance. Callers with dual speakers and dual amplification run through regular alkaline batteries much faster than Foxpro's other units. Use of these NiMH batteries and charger will save money on batteries. This charger/battery set is compatible with AR4, NX3, FX3, FX5, Scorpion X1A, Firestorm, OCC and Fury GX7 and allows charging from the charge jack on the front of the caller unit - no more taking batteries out to charge them. The kit includes 8 AA 'low self discharge' batteries for maximum performance and reliability, and a standard wall charger for home use. This kit will charge completely depleted batteries in about 10 hours.