The Moon Mizar Alcor light set is a great value for money option including USB recharging capability. Both the front and rear light feature easy to remove magnetic twist and lock mechanisms and quality rubber straps in a big and small sizes.
They are very water-resistant once the cap is put on over the recharging plug. Both lights have 5 modes: 2 steady and 3 flash settings with varying intensity. They both weigh less than 20g and last for up to 70 hours depending on the setting.