Bike Handlebar LED Safety Lights, Set of 2 (Purple)

I like these Bike Handlebar lights - but they come in a two pack and one of the two never works...I have bought at least 9 two packs of these (here on Amazon and in a shop) and it's always the same - one works, one doesn't. And the one that works is a bit fragile and will stop working if you turn it on and off a lot. You can get it working again by tinkering with the battery compartment - but I think they are just not designed very well and the unit will lose contact with the batteries after a while - especially if the battery compartment cover bends at all (it's plastic). I still like them though - and am not returning them as I'm sure the batteries in the non-functioning one in each set will be usable later in something else...