This short hub is used for mounting the Angle Grinder accessories noted below. It is included in Kits AK69110, AK69130, AK69130H and AK69130SJ. Many users are unaware that they have the short hub since it is used to mount the flap wheel that comes installed. Press down on the flap wheel when it is removed from the grinder and the short hub will pop out:
1. 2" Sanding Flap Wheels A-2201, A-2202, A-2203, A-2204 and A-2205 
2. 2" Cut Off Wheel A-D11
3. 2" Typhoon Discs ARKB25626, ARKB25627, ARKB25628, ARKB25629
4. Scotch-Brite Radial Bristle Discs (when using only 1 or 2 discs at a time) A-4542-6, A-4543-6, A-4544-6, A-4546-6, A-4547-6 and A-4548-6