Any or all of the above Hair Scare ! There are so many `variables` and `local`factors to be considered.... anything form the quality of the donor-hair, to the amount of processing, to the climate where you live, how often you shampoo, your own body make-up [ oily scalp or excessive sweating] and even the quality of the water used to wash your system.... it`s really a case of `how long is a piece of string...`-- it`s not possible to give an exact answer for the expected-lifespan of a system.....you`ll just have to monitor it for possible lace-fraying, shedding, etc. ..it`s always best to have a stand-by system to hand, in case of a sudden deterioration of any aspect of your current system.