Compu-Verter slide rule consists of white plastic ruler with movable slide ruler inside. Used to convert 8 bit binary to hexadecimal and EBCDIC symbols and card punch codes. Printed red text includes "Compu-Verter / by / MTY computer products, inc / (301) 770-6980". Yellow stain between #2 and #3 on side including "patent pending no. 943925".