These are exact replacements for Hamilton Beach Blender Clutch Drive Couplings. If the rubber coupling on the bottom of your jar is damaged this is what you need.
Installation can be a bit difficult so here's the steps I used for a successful repair:
1.) Remove the blade assembly from the bottom of the blender jar. Remove as much of the remaining rubber as possible from the coupling face. You should be left with a metal disc that has 6 holes.
2.) Use a small wire brush to clean the exposed threads on the bottom of the blade assembly. Apply a bit of penetrating oil to the exposed bolt threads in the center bottom of the blade assembly. Tap the blade bolt bottom (threaded end) lightly with a hammer several times to get the oil to creep.
3.) Adjust a vise so that it straddles the upper blade of the blender blade assembly. Drop the blender blade assembly blade upside down in the vise jaws. Do not tighten the vise; you just want to keep the blades from rotating when removing the metal disc.
4. You will need a tool to remove the remaining metal disc from the blade assembly. A pair of needle nose pliers may work. I used a pair of retaining ring pliers, and reversed the tips in the jaws so that they would be less likely to break. You can also make a spanner tool from a block of wood. Drive two medium nails through a block of wood spaced 1 inch apart. The nails should extend about 1/2" through the block and have their ends ground flat.
Mate the tool with two holes in the metal disc so that they are spaced across from each other (1 inch).
5.) IMPORTANT: The metal disc of the blade assembly uses a REVERSE thread for connection. To remove the disc turn it CLOCKWISE as you would normally tighten a standard bolt or nut. Turn the tool clockwise and remove the metal disc. After removal clean the threads of the blade bolt with a small wire brush. Install the new coupling onto the blade assembly bolt, turning it COUNTERCLOCKWISE to tighten.