Hi, I have an old detex guardsman time clock. It is in a brown leather case and has a clock on the front of it and there are 2 skeleton key holes in it. The front of the clock face reads, " Detex Corporation, Made in the USA, New York, Dedham,Atlanta, San Mateo Guardsman. I found one like it online, and it said it was worth $532.00 - $590.00. Can anyone please tell me anything about it or what it is worth and also where I may take it to sell.