Lights

Blackburn flee?

Bright, small, rear is easy to remove (I assume the front is too) good quality, lifetime guarantee (which works).

I don't know if they've improved but I always remember quality control issues with knogs as well as them not liking the wet. If you're set on hipster-cysts I'd just find some cheap off brand ones.

http://www.evanscycles.com/products/blackburn/flea-front-and-rear-usb-light-set-ec024173

£20.25 with EX10CPA discount code and free delivs.

Just ordered some.