HEPA Bypass Air Filtration System Interlock Kit Use this HEPA interlock kit (X2680) to cycle the HEPA bypass air filtration system (UL - listed HEPA series) with the air handling unit (UL - listed CB Series or CSA - certified G Series). Includes: Current sensing relay (X4421) 24V AC coil relay (56L68) Mounting bracket 18 AWG black wire with two female insulated spade connectors (2) #8 - 32 X 3/8" screws 1/2" strain relief (3) Wire ties (2) 1/4" spade terminals for low voltage connection