Challenge 2 Piece Silicone Front and Rear Bike Light Set reduced to £3 with Free Collection @ Argos

These kind of lights are OK for occasional cyclists and/or as emergency spare lights - they're cheap enough to leave on the bike so you always have them. I have similar ones from Planet X for this purpose that cost the same (plus postage) - they're so cheap that if one gets stolen off the bike it really doesn't bother me.
It's worth having two lights on the back of your bike - one flashing and one steady - in case one dies while you're cycling and also because the combination makes you both visible and easier to judge your distance.
I can't imagine these are very bright - hopefully bright enough to be worth bothering with. And regular use will mean you'll need a constant supply of batteries so you'll quickly find it worth spending more on a USB rechargeable light.
They definitely won't light your way so are only useful as a "be seen" front light.


EDIT - I've just seen that they're 7 Lumens. Planet X will do you a rechargeable 160 Lumen pair of lights for £8.49 plus postage. 160 is excessive for nighttime use (but ideal as a daylight running light) but 7 is very, very poor and probably not fit for purpose. (edited)

Also £2.60 on Fleabay. I have used these for a while to legally comply with the regulations - otherwise I wouldn't bother