ch-4 is the largest fixed wing ucav of the rainbow series (as of end of 2013). externally, ch-4 looks almost identical to general atomics mq-9 reaper, and the only distinct visual difference between two uavs is that the ventral fin below the v-tail on mq-9 is absent on ch-4. there are two versions, the ch-4a and ch-4b. the ch-4a is a reconnaissance drone (capable of a 3500–5000 km range and a 30- to 40-hour endurance) while the ch-4b is a mixed attack and reconnaissance system with provisions for 6 weapons and a payload of up to 250 to 345 kg.