In R.J. Anderson's excellent piece on Danny Farquhar, he mentions that Farquhar has started using a Pocket Radar as part of his training when he throws. 

Farquhar's Instagram houses numerous videos of him using a device called the Pocket Radar Ball Coach -- an instrument he was first introduced to by one of the trainers at his gym.  

Let's dive in a bit on that one. Traditional baseball radar guns that have been used by scouts for years are a bit bulky and aren't very convenient. Pocket Radar, however, as noted in the name, is handheld and fits easily into your pockets. 

Matt Snyder, CBS Sports

That's the newest model, the Smart Coach. It's pretty amazing. Not only is it as accurate as the old school radars, but there's an app that can be synced with the device, allowing coaches to record players throwing or hitting. Each highlight shows the exit velocity (hitting) or throw velocity. Here's a bit of a video explainer: 

In discussing the matter with a local high school coach, who recently won a state championship, he said the best aspect of the Pocket Radar is being able to immediately discuss adjustments with players. For example, a pitcher uses a different arm slot and throws 1-2 miles per hour harder. Immediately, there's a number on it; a substantive way of making the player believe this way helps him. 

The radar is making waves in high school and college baseball, but as noted in the case of Farquhar, many professionals are starting to find it useful as well. Obviously, the scouting community is starting to catch on as well. It's a pretty fun little device that baseball fans might start seeing more and more moving forward.