Shimano's Deore XT SL-M8000 Rapidfire Plus Right Shift Lever features a 2-way multi-release mechanism to provide a secondary gear change option whilst an improved Vivid indexing mechanism guarantees shift accuracy. The I-Spec B-type (SL-M8000-B-I) suits older or lower grade brake levers and will instantly release the cable when the trigger is activated. The ergonomic design of the shifting lever is big news for endurance athletes who can expect a 20% reduction in the shift force required to initiate gear change options. It's a very simple way to make big changes to your gear changes.