Namsan Dog Puppy Doggie Pet Transparent Flashing Lights Nylon Collars (Small,Medium,Large,Extra-Large) & (Yellow,Red,Blue,Green,Orange,Pink,White,Colorful) Neck Size: 40-48cm Width: 2.5cm Width 2.5cm (1 Inch),Every size 8cm flexible range. Can adjust the length by yourself Three modes:1.Steady On 2.fast flash 3.normal flash 60 hours steady light time or over 100 hours flashing time Any thing please feel free to contact us