From the Bunnings website:
Customers can trade in only one battery for each twin pack. Valid from 1st May 2023 to 30th June 2023. Please refer to T&C's below before making your purchase.
Valid for $50 off:
* AEG 5.0Ah 2 pack $299
* Makita 5.0Ah 2 pack $319
* DeWalt 5.0Ah 2 pack $269
* Bosch 5.0Ah 2 pack $289
* Hikoki 5.0Ah 2 pack $269
* Metabo 5.0Ah 2 pack $279