1. Cap-sieve plates are highly effective contact devices. 2. The capacity of cap-sieve plates is higher than that of cap plates and lower than that of sieve plates. 3. Cap-sieve plates ensure stable operation under considerable variations in load and, hence, are broad-range plates. 4. Owing to the special features of the hydrodynamic interaction between the phases, the amount entrained from the plates is relatively small in the admissible load range, and the spacing between the plates may be reduced.