Two Herman Miller Chairs

Yesterday a neighbor contacted me to see if I wanted any items that were stored in a storage unit before they hauled them all to the city dump. She said to take want I wanted and when I saw the two chairs, I had to have them. They were in storage for a number of years and are in excellent condition. Apparently, they were used at Mountain Bell. They are embossed Herman Miller and his emblom on the bottom. A black stamp is also on the bottom with a number I think it's 501?92; a small square stamp that I think says U.S. with an S in the middle and summit at the bottom. There is a silver sticker with 18032 which may be the inventory number. Molded white chairs with a navy blue padding. Four chrome bars makeup the pedistal and there are 4 plastic sliders on the base of the pedistal. It's all original with no rips, tears, or stains. They barely appear to be used at all. Any information you can share with me would be appreciated.