Abstract: A coupler assembly for coupling first and second roller tubes together includes first and second side assemblies. The first side assembly includes a clutch mechanism having first and second clutch members supported on a shaft for movement between a closed clutch condition in which the roller tubes rotate simultaneously and an opened clutch condition in which the tubes are uncoupled for relative rotation. The clutch mechanism includes a clutch drive member preferably including an elongated bar slidably received in an elongated groove defined on an exterior surface of the shaft. The clutch drive member may include a lug received in an interior of the second clutch member to apply a pulling force to the second clutch member. Alternatively, the clutch drive member may include a thrust member contacting the second clutch member to apply a pushing force.