Fit

The Sportviz Core has a curved fit that wraps around the face. These sunglasses provide a good fit regardless of the activity.  The large width to the lenses may cut down on the style points for some users.

Comfort

I found these glasses to not be as comfortable when compared to others in this category.  The frame stayed in place well, but overall I found these glasses to be a bit heavier that others and less comfortable.       

Lens

The clarity of the lenses were good and the landscape details were crisp and easily discerned. Sportviz claim the XTS to have UV400 protection (100% blocking of UVA and UVB) which blocked glare very well on snow and on rocky terrain in the mountains.  The wider design of the glasses also provides extra lens width which helps block light and glare from the side.

Coverage

The Sportviz Core provides good coverage due to the wider lens, which helps make these sunglasses versatile enough to use on a variety of outdoor activities.  This coverage excelled at blocking wind and sun from both sides.

Features

The Sportviz XTS Core are designed to be able to add your prescription lens to these glasses.  This technology is called an Inzert, which allows you to have the technology of a pair of sunglasses with the vision capabilities of your prescription lens.   I find this to be an excellent feature for those that need prescription glasses to really get the most of your outdoor experience. You can also utilize these glasses without the added Inzert, or one with a added clear protective lens.