Professionals Choice Bob Avila Signature Series Roller Port Calvary Shank BitProfessionals Choice Bob Avila Signature Series Roller Port Calvary Shank Bit Product Number : AVPC 262 This bit is a replica of a bit that Bob has in his collection. The original bit was an actual US Calvary bit, which was extremely popular with bit makers from the 1960s through the 1980s. They would often find the Calvary bits in antique stores or garage sales and then add fancy silver and or conchos to them. The bits are highly sought after and are