Correct size:dog harness with adjustable chest strap,to ensure your dog's safety and create a custom fit for your size dog,S: neck 42-54cm, chest 50-66cm. M: neck 58-72cm, chest 56-76cm. Size L: neck 62-80cm, chest76-110cm. :The product does not contain button batteries,you must use your own,there are three levels of adjustment, double-click the first time for continuous light mode, then click once for continuous flashing mode, then click once for alternating slow flashing mode, and finally click once for power off Safety Control:The double handle at the top of the harness lets you safely control your dog-stop him or direct his movements on the street,There are two metal rings on the chest and back. The front ring can be used to hang dog tags or ornaments. The rear ring is used to hang the leash.The pulling force is distributed evenly over the body, largely reducing pulling and strangling. Omnidirectional Safety Features:Our dog harness is made from 1680D double Oxford fabric with a lightweight EVA lining and padding,Soft and comfortable,for a brilliant feel and robust abrasion resistance.With strong stitching,thicker D-rings,thicker closures,double strap handles,a velcro area on the belly where you can attach badges of different shapes. Safe attachment:The back is secured with velcro and flashing clips that make it more stable and reduce the likelihood of it coming loose.