#279XT Smoke Spec (does not include lenses) The #279XT Smoke Spec insert with extension bracket. Click here for the Smoke Spec Insert Guide for examples of compatible masks. Click here for insert specs. Instruction Page #279XT Smoke Spec quantity Add to cart Category: Uncategorized Related products Prescription Bifocal LensesPer Pair – Free USPS First Class Shipping – (Near vision segment = 28 mm wide x 19 mm high) $95.00 Add to cart Reading LensesPer Pair – Free USPS First Class Shipping – (Reading vision segment 28 mm wide x 19 mm high) $45.00 Select options