Topeak RedLite II Tail Light Used by both professional and amateur riders alike Made using high quality materials and components Tested to ensure quality and durability 4 Red LEDs, (2) CR2032 Battery (Included) Control 2 Modes Constant/Blinking Burn Time (approx) 60 hrs/100 hrs Size (L x W x H) 5.4 x 5.5 x 2.2 cm / 2.1" x 2.2" x 0.9" Weight 20 g / 0.70 oz (light only)