So, you’re buying a pair of
Understanding the Size Specs:
Sunglasses have a few different specs that are most important to how they are built for size and how they will fit you. Nonetheless, the most important size spec is the lens width.
Temple:

The temple means the arm (or leg,) of the sunglasses. Usually, these range from 115-145mm.
Bridge:

The bridge is middle piece of the frame that sits on your nose between both eyes that determines distance across both eyes. This can range from 10-18mm (all averages.)
Lens:

The lens is just that, the lens part of the sunglasses. This size is always measured by width but some resources will give you the height as well. These can range from all types of sizes.
Different Ray Ban Wayfarer Styles:
It’s important to note there are a few types of Ray Ban Wayfarers available as styles by codes. For example, the classic
Classic Ray Ban RB2140

The Classic Ray Ban Wayfarers, RB2140, come in three different sizes, 47mm, 50mm
Sizes:
47mm: Small fit
50mm Medium fit
54mm: Large fit
The RB 2140 is now also available in asian fit which the code for that is RB 2140F. The Asian fit brings a tighter fit so the bridge of the sunglasses are smaller, the lens size is 52mm: Small/Medium.
New Ray Ban Wayfarer RB2132

The RB 2132 is a great seller and considered and called the NEW Wayfarer as it brings a more modern look to the classic frame. This frame comes in two sizes.
Sizes:
52mm: Small-Medium size fit
55mm: Large fit
Folding Ray Ban Wayfarer RB4105

The Ray Ban RB4105 brings the classic shape of the Wayfarer but foldable. This frame also comes in the same dimensions / sizes as the classic RB 2140:

Sizes:
50mm: Medium fit
54mm: Large fit
Liteforce Ray Ban Wayfarer RB4195
The Ray Ban 4195 is a new modern touch to the classic frame. These are called the Wayfarers Litforce because of its material, thermoplastic, which is incredibly light.
Sizes:
52mm: Medium fit.