The Quick Verdict
Get the Garmin Approach Z10. It's $60 more than the Nikon COOLSHOT 20i GIII, but that gap buys you more range, tighter accuracy past 100 meters, and Bluetooth, Range Relay and a cart magnet the Nikon doesn't have. The COOLSHOT 20i GIII is worth a look if you prioritize weight above everything else — it's noticeably lighter — but for most golfers, the Z10 is the better tool. Check price at PlayBetter →
What They Have in Common
Both shoot at 6x magnification, hold ±1 yard accuracy out to 100 meters, and include slope mode with a toggle to turn it off for tournaments. Both take a CR2 battery — easy to find, easy to replace mid-season. Garmin rates the Z10 IPX4; Nikon calls the 20i GIII rainproof without an IP rating. For core rangefinder duties, they're working from the same foundation.
Where They Differ
Display and Optics
The Z10 uses a transparent PDLC display with a black readout. The COOLSHOT 20i GIII uses an internal display, and Nikon lists a multilayer lens coating. I haven't used them side by side, so I won't tell you one is easier to read; my guess is the difference comes down to what you're used to more than to either spec.
Range and Accuracy
The Z10 reaches up to 350 yards to a flagstick and out to 1,200 yards on reflective targets. The COOLSHOT 20i GIII tops out at 800 yards total. For most golfers playing courses where a par-5 second shot rarely exceeds 220 yards, 800 yards is plenty. But the Z10's accuracy spec holds at ±1 yard throughout its range; the COOLSHOT 20i GIII is ±1 yard only inside 100 meters, then widens to ±2 yards beyond that. On a 175-yard approach into a pin tucked near the front of a green, two yards can be the difference between a good swing thought and a guessing game.
Smart Features and Connectivity
The Z10 brings things the COOLSHOT 20i GIII doesn't: a cart magnet built in, Bluetooth to the Garmin Golf app, Range Relay (which sends ranged distances to a compatible Garmin watch, handheld or the Garmin Golf app), and a Find My Garmin function if you set it down somewhere dumb and walk away. These aren't gimmicks. Vibration lock is genuinely useful when you're not sure the reticle settled. The cart magnet means you're not digging through a pocket every time. Nikon lists LOCKED ON QUAKE lock confirmation and First Target Priority, but no magnet and no Bluetooth.
Weight and Warranty
Here's where the COOLSHOT 20i GIII earns some real respect. It weighs 4.6 oz versus the Z10's 6.3 oz. That's a meaningful difference in your shirt pocket over 18 holes. Nikon backs it with a five-year warranty. I couldn't confirm Garmin's warranty for the Z10.
Who Should Buy Which
Get the Garmin Approach Z10 if:
- You want ±1 yard accuracy all the way out, not just inside 100 meters — especially on longer approaches where you're already hunting for a small flag.
- You ride in a cart and want to stick the rangefinder to the frame between shots — the Nikon has no built-in magnet.
- You're already in the Garmin ecosystem and want Range Relay to push distances to your Garmin watch, handheld or the Garmin Golf app.
- You're the 14-handicap who plays different courses regularly and wants the extra range and tighter accuracy for those 180-plus-yard carries into unfamiliar greens.
Get the Nikon COOLSHOT 20i GIII if:
- Weight is your actual priority — 4.6 oz in a shirt pocket feels meaningfully different from 6.3 oz by hole 15.
- You play the same course most weekends and know your yardages well enough that 800-yard max range and ±2-yard accuracy beyond 100 meters don't change how you play.
- You're buying your first real rangefinder and don't need Bluetooth or app integration cluttering up the experience.
The Bottom Line
The Z10 is the better rangefinder. The longer range, tighter accuracy throughout, the cart magnet and the Garmin smart features add up to a device that earns its $60 premium. The COOLSHOT 20i GIII is lighter — that's a real trade-off, not a throwaway — but the core job of a rangefinder is giving you a confident number fast, and the Z10 does that better. CR2 batteries are at every pharmacy in the country, so the "up to 1 year" battery life on the Z10 isn't a risk. Buy it, carry a spare CR2, and stop thinking about rangefinders.