Two bright LEDs Easily slides over your dog's neck as a bright LED addition to an existing collar Universal sizing: cut to fit from 12" - 27" | 30.5cm -68.5cm Glow and flash modes 360° of illumination Battery run time: 60 hours Weather resistant 2x replaceable 1154 batteries (red LED) or 3x replaceable 1154 batteries (blue, green, pink LED) included Battery run time: 60 hours Dimensions: adjustable length 12" - 27" x .3" | adjustable length 30.5 cm - 68.5 cm x 7.6 mm Weight: 2.1oz | 59.5g