I buy this in late September -lrb- month and a half ago -rrb- , have not use it a lot but it make I start ache really fast . I have discover though , it you keep go for about 10 minute the ach go away and from then on I do not really get more wear out , I just keep go and go and get bore after 20 minute . the thing that really bug I about it be how noisy it be , the air contain in the bellows on each end have to go somewhere so there be a little hole in each one that make the air hiss rather loud at the end of each stroke .