I say 'extra' because a Model 4/5 purchase does already include a complimentary Pencil Dock. But, some people have asked for additional docks... so I've added the option to purchase these as well.
The dock is machined Polyacetal plastic with a silicone insert that provides an anti-slip base on the bottom and a pencil tip cushion on the inside of the dock.
When purchasing, please select the proper size at the bottom left (8.3mm dimater or 9.2mm diameter).