I was wondering this as well. Looking at their website, it looks like only Avantree rechargeable batteries work, but I'm not sure why: https://avantree.com/product-support/WSH...-batteries
Maybe there is some "secret ingredient" involved haha.
Also, I was able to find the batteries on the UK site here: https://avantree.com/uk/battery-for-ht280
Maybe there is some "secret ingredient" involved haha.
Also, I was able to find the batteries on the UK site here: https://avantree.com/uk/battery-for-ht280