Difference Between Bluetooth 3.0, 4.0, 4.1, 4.2, & 5.0

Bluetooth, clases y versiones desde v1.0 hasta v5.0
https://www.330ohms.com/blogs/blog/que-es-el-bluetooth

Difference Between Bluetooth 3.0, 4.0, 4.1, 4.2, & 5.0
http://majorhifi.com/the-difference-between-bluetooth-3-0-4-0-4-1-4-2-explained/