Hollow compression battens are used in full-length pockets from the luff to the leech of the mainsail in highly loaded areas like as supporting the head of a square top mainsail or connecting to mainsail cars.
Flex battens are long intermediate battens, these are hollow at one end and taper down to a solid section. These are used as leech battens when low stiffness is required at the inboard end.
UltraFlex battens are shorter solid plate battens for controlling the leech of the sail, most commonly called “flutter” battens. These are our lightest and most flexible battens.