A downhole tool (10) comprising rotatable inner and outer sleeves (62, 63). The sleeves (62, 63) comprise coupling portions for transmitting a torque between the sleeves (62, 63). The tool is reconfigurable between a first configuration whereby the coupling portions are axially misaligned to prevent transmission of torque between the inner and outer sleeves (62, 63), and a second configuration whereby the coupling portions are axially aligned to permit a transmission of torque between the sleeves (62, 63). At least one of the coupling portions is configured to prevent the transmission of torque above a predetermined torque threshold.