My indoor (non Transitions™) multifocus² glasses are CR-39¹. I'd used the same material for my outdoor/sports/driving frames but it's higher density caused the

My indoor (non Transitions™) multifocus² glasses are CR-39¹. I'd used the same material for my outdoor/sports/driving frames but it's higher density caused them to slide down my nose during activity so the next pair I opted for Trivex. -- ¹–CR-39 requires full frame spectacles, as drilling holes is verboten. ²–Shamir Autograph III, awesome & highly recommended.