Packable, Lightweight Core Body Insulation The original Pro SL Primaloft Gilet was a game changer, bringing technical hollow fill insulation to the performance cycling market in the form of a versatile, packable gilet. The updated version, the Pro SL Primaloft Gilet II, is even better with improved breathability, stretch and an updated, contemporary design. Two different types of Primaloft fill have been used. 80g of Primaloft Gold has been used on the front torso, maximising insulation exactly where you need it most. 60g of Primaloft Silver Active has been used on the back, giving improved breathability and accomodating some stretch to create a great fitting garment. PrimaLoft insulation boasts an exceptional warmth to weight ratio, tiny pack size, extremely breathable construction and is highly water resistant making it a tremendously versatile performance insulator.