A fine pair of Georgian mahogany wine coasters or bottle sliders.
They were used for placing decanters in on the dining room table to prevent drops of wine landing on thje table and would be slid down the table for people to help themselves. They also prevented the glass decanters from knocking against each other.
This is a particular nice pair with wavy rims and brass inlay.
Dating from around 1780/90.
 
The coasters are each large enough to take a magnum decanter with a maximum diameter of 18.1 cm, and with internal diameters of  16.5 cm.   Height is 1.8cm.