The head lasts up to 3 months of use , after which they begin to fall apart, lose their effectiveness and, in addition, bacteria accumulate on them. Fortunately, the heads are equipped with blue bristles that fade after 3 months, so you know its time to replace the heads. Compatibility TrueLife SonicBrush K series. Try other products of the TrueLife brand, which you can find in the categories Electronics under the tree, Toothbrushes and Mouth and teeth. You can now buy the product with a 0% discount. If you are not sure which product to choose, get inspired in the category Sonic toothbrushes for adults.