Just so everyone knows...
Cleansing oils and cleansing balms (oil-based) should not be used with silicone brushes. The oil will cause the silicone to breakdown and ruin the surface of the device. I found that out the hard way when my Pop Sonic Spade started to shed some of the bristles. If you insist on using oil-based cleansers with a silicone brush then at least wash it off with some regular cleanser before putting it away. That's what I'm doing and it seems to be fine. Leaving oil on silicone for long periods of time is when you will run into problems with the silicone degrading so wash it off when you're done.... a double-cleanse for your brush.
ETA-
The oil cleanser 'warning' is mentioned on Foreo's website under their FAQ section.