Boards are not drilled so they will fit any ring and back frame.
The boards are available in the following sizes
Special practice size 1.2m x 0.6m (4′ x 2′)
Practice size 1.2m x 0.9m (4′ x 3′)
Regulation size 1.8m x 1.05m (6′ x 3’6″)
Old regulation size 1.8m x 1.2m (6′ x 4′)
Price per board
If you are replacing an old regulation board with the current regulation size check there will not be any exposed frame protruding beyond the new board as this can create a dangerous obstacle.