The exposure flash front light is extremely easy to use simply rotate the head to turn the light on and off this light offers 110 lumens making it bright enough to see your way home when riding in low lighting conditionsit39s fully sealed and it will provide you with 35 to 20 hours of runtime the light is 56mm long so it will easily fit in a jersey pocket or a saddle bag when you39re riding during the day this front bike light can be used with either disposable or rechargeable batter