If what you are looking for is a simple and cheap front or rear light but that still makes you visible in the city, the Union 101 is the set for you. Weighing just 17 grams and measuring 15 x 20 x 64 mm, it's the perfect light to keep in your pocket when you leave your bike parked on the street. It is waterproof and has a battery life of 2.5 hours. It is charged via USB port and includes a strap to fix it on the handlebar, saddle or seat post. Simple but effective.
Union products have a very good reliability: they have a good longevity and durability. Also, the relation quality-price is very good, you'll have a product that will last you years without spending a lot of money. That's why we decided to sell their products, it's a trusty brand that we can recommend.