[Break through traditional running vest fabrics] Hydration vest with a weight of just 140 g (5 oz) and a size of 13.3 x 9 inches,It adopts highly elastic perforated fabric, which offers visible lightness. It truly enables a comfortable fit, allowing for a free - stretching feeling on the body while also being highly absorbent of sweat and breathable. The adjustable webbing around the vest can comprehensively wrap the body, so you can run as freely as the wind [Breathable and Adjustable] Breathability is enhanced using lightweight mesh. Skin chafing is avoided by the race vest's soft shoulder strap edges. The chest clip can be slid up and down to a position that suits your body. Pull the waist webbing to a comfortable position and then fasten it with a black elastic tightening ring. This is suitable for both women and men runners. There's no need to worry about choosing the right size, as it's applicable to the whole family [Practical Hydration System] A 1.5-liter hydration water bladder that is both leakproof and blowproof is included with the running backpack.The large zippered compartment is designed for a 1.5L hydration bladder. Inside, the hydration backpack is also a strong waterproof cloth for separation. You can place items such as coats, towels, cosmetics, keys, earphones, wallets, and energy bars in it, without having to worry about the items getting wet from the moisture on the bladder