AP Explosives manufactures cord relays. Cord relays provide accurate delay between blast holes in a row or cross in a multiple row blast. Cord relays are of 2ms delay detonators of the same delay timing placed in opposite direction specifically designed plastic component.
Cord relays are bi-directional. The plastic component has a provision for hooking of detonating cord at either ends. The delay timings are printed on the plastic component.
These are used in conjunction with detonating cord trunk lines in open casts, coal mines, quarrying, civil construction, underground metal mines.