Cressi Focus Mask Prescription Optical Corrective Lens -1.0 to -8.0 - Cressi: Italian Quality Since 1946 Cressi is a REAL diving, snorkeling and swimming Italian brand, since 1946. Optical Lens for Cressi Focus mask. Only one lens per order. Choose your Diopter Correction lens for Left or Right eye. Made in Tempered Glass. Made in Italy. OPTICAL LENS SOLD INDIVIDUALLY.