Some classic rubbers have the conversion on the back of the package:
https://pt.aliexpress.com/item/10000156731716.html?spm=a2g0o.cart.0.0.6a497f06Srp30c&mp=1&gatewayAdapt=glo2bra
But I've never tested Bloom's power, maybe it's harder than advertised or has quality control issues