For auction is a huge assortment of Keystone visual diagnostic and treatment cards. As near as I can tell, there are cards from the Keystone Visual Survey Series and from the Keystone Occupational Service Series. There are over 200 cards in all - 156 full cards and 73 half-size cards. Many of the cards are numbered sequentially for bot the left and the right eyes and all cards are in excellent condition. It is rare to find this number of Keystone cards of this type.