This is a little too snug for me so I moved up to a large. Only wore around house new condition. Alpinestars Bionic Tech V2 Protection Jacket Incorporating innovative grid protection technology that is lightweight and ventilated, the versatile Bionic Tech V2 Jacket has CE-certified protectors incorporated into the slim, stretchable material for high levels of comfort. Compatible with Alpinestars Bionic Neck Support and with the Bionic Hydration Pack. Features: Slim stretchable fabric for a comfortable fit Floating, highly ventilated and flexible rigid Chest Protector with flexible side wings that adapt to the rider’s body Central front zipper for a better fit Additional front padding on the arms, sides and chest for enhanced roost protection High abrasion resistant fabric on the arms over the protectors for additional protection Height adjustable kidney belt for optimal levels of fit BNS compatible with a removable back puck panel and elastic BNS cords on the shoulders straps New Cell Technology back protector is highly ventilated and flexible for enhanced rider comfort Bionic Hydration Pack compatible