RP-N two-way action relay is designed for providing delays in blasting circuits of detonating cord in surface blasting and gas and dust safe underground mines and pits. It has 3 delay series: 20, 35 and 50 ms. Identification of delay series is performed by differentiating painting (marking) of relay cases. RP-N-20 relay with  20 ms delay has a red case, RP-N-35 relay with  35 ms delay has a white case, RP-N-50 relay with  50 ms delay has a black case. The relay consists of two delay blasting caps connected by a plastic bushing through crimping. Segments of DShV detonating cord of 30-50 cm are crimped at loose case ends. Case is made of steel with pinchbeck covering.

    Relay is connected with detonating cord by a knot or through lapping with isolating tape or packthread. Relay is shipped in boxes, containing 260 to 300 relays. UN number: 0029. Classification code: 1.1 B.