Two bright LEDsEasily slides over your dog's neck as a bright LED addition to an existing collarUniversal sizing: cut to fit from 12" - 27" | 30.5cm -68.5cmGlow and flash modes360 of illuminationBattery run time: 60 hoursWeather resistant2x replaceable 1154 batteries (red LED) or 3x replaceable 1154 batteries (blue, green, pink LED) includedBattery run time: 60 hoursDimensions: adjustable length 12" - 27" x .3" | adjustable length 30.5 cm - 68.5 cm x 7.6 mmWeight: 2.1oz | 59.5g