one end pop out the spring , make it lop-sided and unable to be use . that only happen after use it maybe a total of 3 time . it be a shame too because it be start to work under my arm -- I could feel it . guess i 'll have to return it now , dang it . not worth the hassle . I should have just get it from the drugstore here , Rite Aid , for the same price . return it to they would be less of a hassle than do it through the mail .