This package includes 17 species transistors in common use.It's convenient for you to make some small designs.You could find a suitable one for your type! A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.It is composed of semiconductor material with at least three terminals for connection to an external circuit.A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals.Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal.Get one pack,convenient for your next project! 

As this pack is packed manually, maybe one or two are differences in quantity.Sorry for that.