for the advantage it is well worth the cost
the 3 star rating is simply because it is a current day product and was not made with the 1950's mentality.  to where it would never need to be replaced.  I have owned 6 of these all 6 have broken in time, but I will buy another one in a hot minute as the help it gives is well woth the cost.  I really can't do with out this device, even the salesman at JC Penneys wanted one like it.
Rating: 3 stars