Frio's keep insulin safe even in hot climates. Choose the product size that is right for you: DuoPen-Dimensions: 83mm x 180mm (3.27 in x 7.09 in) Holds: combos of pens, vials, cartridges::a) Two insulin injection pens either pre-filled disposable pens or refillable pens, OR b) One insulin pen plus 2 x 3ml cartridges or one insulin pen plus 3 x 1.5ml cartridges, OR c) 2 x 10ml vials of insulin & injection syringes