As less people are using their tumble driers at the moment, mostly due to the high cost of running them.Dont let your tumble drier sheets dry out. Firstly once you've opened the box always put the box in a sealed plastic bag to keep them moist and I use them all over the house, on radiators, in with dry towels in the airing cupboard, in my hoover bag and also just under my car heater vent, when I put my winter or summer clothes away I always put some in with them too. The smell is lovely all over the house and lasts quite a while.
