Three sets of four risers. Please specify which set or sets you want.
Set A - Wooden blocks with a rise of c. 8cm. The round recess in the block is 7cm in diameter.
Set B - Small plastic. Rise of c. 9 cm. The round recess at the top has a diameter of 7.5 cm.
Set C - Large plastic. Rise of c. 10.5 cm. The square recess at the top has sides 8cm long.
Update: Set B assigned. The other two sets are still available.