The thermos flask cleaning sponges (also named isolating flask cleaner or bottle brush) are getting more and more popular, and we are able to deliver them loosely or ready for selling with handles. The possible shapes reach from cylindric, rounded on top till rounded on top with cleaning grooves at the outer diameter. The cleaning grooves are meant for heavy pollution outtake.
Actually the most popular thermos flask cleaning sponges consist of two different sponge qualities, a soft sponge (yellow) and a stronger, big pored one (blue or green), that guarantees an effective cleaning of heavy pollution.
The additional benefit is it´s universal usability: It´s getting used for rims for cars or motorcycles, flower vase, glassware and many other applications.
The advantage: No circumstantial cleaning of the rims and no contaminated hands because of the distance to the rims.