Halo/Morningstar Spin Doctor Grease Injector tool.Specially developed by Morningstar tooling, this relatively simple tool allows long lasting grease to be pressure injected inside the bearings and pawls of the Spin Doctor freehub - without the need for complete disassembly.To Grease:Push-in the Freehub injector tool into the end of the freehub and apply grease into the tool via a grease gun, until you can see a small amount grease purging out of the backside of the freehub. Hi quality grease injection will provide long lasting lubrication.This tool can also be used to purge a contaminated freehub of old lube, water and grit.(Simply continue injecting excess grease, and the excess grease will be forced out of the back of the freehub, taking with it existing contaminants.)Note:2007 series Spin Doctor rear freehubs have genuine Finish Line TFG37 grease packed inside, plus a \"lube hole\" concealed under the cassette sprockets. To lube the pawls and bearings, simply remove the cassette and insert a grease gun pointed nozzle and squeeze! (Note: no need to pull-off hub end seals or use this special injector tool - but it CAN still be used if a full purge is required.)