Garmin has entered the on-course stat-tracking market with the company's new Approach CT-10. Insert the nine-gram sensors into the grips of your clubs, and sync with two options of Garmin GPS golf watches, the Approach S20 ($200) or the Approach S60 ($400). As you play, the sensors, connected to the watch via Bluetooth, track each shot you hit—sort of similar to the Arccos or Game Golf systems, except everything is displayed through the watch device, rather than the app. As you play, data about your game is collected, so you can use it to inform your decision-making on the course. The average distance you've been hitting each club, for example, is calculated. This eliminates some of the guesswork in club selection. When you're standing over your ball and checking your yardage on your watch, you can also see which club actually goes that distance.
Other stats being tracked are greens and fairways hit, and strokes gained. To calculate strokes-gained data, Garmin used Mark Broadie's paper on how strokes gain is calculated on the PGA Tour as a baseline. The calculation that Garmin reaches to determine your strokes gained is relative to other golfers with a similar handicap to yours, so you're easily able to compare different aspects of your game to those of relatively similar ability.
You can also upload the data from your rounds to the Garmin Golf App (which is free). Through the app, you can compare yourself to friends and other golfers in the area, and you can also set up games or tournaments.
The Approach CT-10 is available in two different sets: The starter set, which includes three sensors ($80), or you can buy a full set that includes 14 sensors ($300), in addition to one of the watches.