Conversion kit of 5 modular cups (2 are free) size M for the Mini Biobox, designed for converting the EasyBox (size XS) filter cartridges system into the new B-BOX modular system of biodegradable filter cartridges. All the older versions of the Mini Biobox filters can be upgraded with this compatible conversion kit. Made from 100% recycled plastic and 100% reusable, this conversion kit is compatible with the Mini Biobox 1 and Mini Biobox 2 filters.