This is for a vintage rodeo contestant pin from the 1964 Odessa, Texas Rodeo.  These were issued to contestants, and the number would match the back patch assigned to each contestant. This is #663. This was originally issued to Bob "Flash" Eidson and was purchased from his estate following his death in 2013. Measures 1 3/4" in diameter. Back side has some tarnishing. 
 
About Bob "Flash" Eidson: Eidson began competing in rodeo at the age of 16. From 1958 through 1972, he competed at the highest level of ProRodeo, and was a three-time qualifier for the National Finals Rodeo as a bareback rider (these in 1962, 1963 and 1964). He finished sixth in the world in both 1962 and 1964. He was also a three-time NFR judge, and was a judge in a number of other rodeos around the country. He retired in 1974, and went on to work for the PRCA (Professional Rodeo Cowboys Association), when he served as General Manager for over a decade before his full retirement in 1988.