Serfas Thunderblast Headlight (USLA-7BK)

$55.00 SGD

Besides being extremely bright and visible tail light, the Serfas Thunderblast tells you with an audible 85 Decibel alert when the light has about just 10 minutes of run time left. Super useful if you hate to run out of light battery when riding.


  • “Blast” Audible Low Battery Indicator Alerts Rider Of Low Battery
  • New Body Design Easily Fits Aero Applications
  • Low Flash Lasts Up To 14.5 hours
  • Extra Long Mounting Straps For Endless Mounting Options
  • Specs:
  • Solids Modes: High (40 Lumens): 2.25 hrs & Low (10 Lumens): 7.75 hrs
  • Flash Modes: High (40 Lumens): 4 hrs & Low (10 Lumens): 15.25 hrs
  • Weight: 48 Grams Without Bracket
  • Battery: USB Rechargeable Li-Polymer
  • Thunder Blast Tail Light Instructions

How It Works

When the battery reaches 10 minutes of runtime, in its current mode, the light will emit a long beep followed immediately by a short beep. Sound will continue every minute.

When the power button is pressed it will put the light in the next longest running mode & it will restart the battery low alert until 10 minutes of runtime in the mode is reached. Repeat as necessary. Example: Going from highest mode to lowest mode at first beep could extend runtime up to 5 times.*

Light will emit beep sound repeatedly when last minute of runtime in the current mode is reached.

While charging the light the power button will blink blue. When full charge is achieved light will beep to notify charging cycle is complete.

Light emits a beep when power button is pushed & light goes from mode to mode.