According to Hockey Gods the game of Bandy Ball:
Bandy Ball is played on ice, using a single round ball. Two teams of 11 players each compete to get the ball into the other team’s goal using sticks, thereby scoring a goal. The game is designed to be played on a rectangle of ice-field which is the same size as a soccer field.
Bandy Playing Rule 2.1 The ball:
The ball shall be made of approved material in an easily visible colour. When dropped on firm ice from a height of 1.5 m, the bounce shall be regular, 15 cm at least and not more than 30 cm. The diameter shall be 63 mm +/- 2 mm everywhere, and its weight shall be at least 60 g and not more than 65 g when unused.
Bandy Playing Rules – http://www.worldbandy.com/ckfinder/userfiles/files/Rules/Internationella-bandyregler-12.pdf
Photo – http://hockeygods.com/hockeys/15-Bandy