The RB4221 shares the square plastic family with the RB4198 but runs slightly smaller, at a 50mm eye size and 145mm temples — the exact figures this lens pair is cut to, since even a few millimetres' difference changes how the edge seats in a plastic groove.

TAC and polycarbonate are both available, cut to the RB4221's own bevel so the lens clicks into place without the gap a lens sized for its 55mm sibling would leave.

Frequently asked questions

What's the warranty if a lens pops out or discolors after a few months?

All lenses are independently made and carry a 3-year warranty against manufacturing defects — if a 50mm lens fails to seat correctly or the coating degrades on its own rather than from an impact, we'll replace it free.

How much does it cost to replace lenses instead of buying a new pair of sunglasses?

A pair of 50mm lenses for the 4221 starts at €25.00, a fraction of a new Ray-Ban frame, and shipping is free worldwide with no minimum order, so the total stays close to that price.

How hard is it to install replacement lenses myself?

Most Square frames use a simple press-fit: flex the frame slightly, seat one edge of the 50mm lens into the groove, then work your thumb around the rim until it clicks into place — no tools needed.

Do replacement lenses block UV rays as well as the ones they're replacing?

Every lens we sell, including each option among the over 15 lens colours, including mirrored and polarized options, blocks 100% of UVA and UVB radiation, so changing the color or finish on your 4221 never means sacrificing sun protection.