The best way to protect your smartwatch is by using a Smartwatch 42.5mm PanzerGlass. Here's a great deal from a reputable manufacturer that has optimised the glass to protect the screen, and it's made to a solid quality.

Features of this glass 42.5mm Smartwatches:

• Excellent protection against scratches and tears.
• Superb screen protection in case of watch loss.
• Super thin tempered glass with a thickness of just 0.2 mm.
• Good quality.
• 'Anti-fingerprint' technology keeps fingerprints, dust and other impurities off the screen.
• Anti Bacterial - Fights the bacteria that settle on the glass. 
• Waterproof / Moisture resistant
  
• Easy to assemble.
• Cleaning kit for the screen before mounting is included.

You greatly minimise the risk of scratches and tears to the screen when using this type of Smartwatch Screen Protection, which is produced in a good quality.

Suitable for:

- Polar Vantage M
- Suunto D5
- Suunto 9/9 Baro