This Quality Scuba Diving Mask is a fantastic state of the art mask which is ideal for comfort and performance! Good for scuba diving and/or snorkeling. Ideal for medium faces (fits almost everyone). Optical Lens CODE RX001 Ideal for medium faces (fits almost everyone) Crystal, liquid silicone injected skirt and strap Double edge comfort seal Ultra low volume Broad peripheral view Tempered glasses Optical lenses available from -1.0 to -10.0 by increments of 0.5 (for near sighted) Optical lenses available from +1.0 to +4.0 by increments of 0.5 (for far sighted) Bifocal lenses available from +1.0 to +4.0 by increments of 0.5 (gauge reader) Please note there will be an additional 2 to 3 days processing time for most RX lenses Returns are not accepted for used lens. Only unused lens are eligible for return with store credit.