The K "Series 60" scopes were introduced in - guess - 1960. Believe they introduced permanently centered reticles and improved adjustment mechanics. There were further improvements made in the Series 60 line indicated by a letter suffix. The K-10 I have is a Series 60-B scope. The K scopes were available in 1, 2.5, 3, 4, 6, 8, 10, and 12 magnifications, and there was also a rather primitive variable, the KV (2-3/4X to 5X). I wouldn't call the K-8 a general purpose scope; the field of view is small, light gathering ability mediocre, and eye relief/eye position is cranky compared to newer scopes. The 8's, 10's and 12's are best suited for varmint shooting or paper punching