Horolovar's Kern miniature bottom block. Used on Horolovar suspension units 12C, 12D, 12E, and 12F. This block is thinner than other blocks. It can also be used on other manufacturer's suspension units.
We can help you find the right blocks for your clock, assemble your suspension unit to the proper dimensions, install the suspension unit on your clock, and put the clock in beat. Any questions, just ask!