Also, regarding the USB version I posted further back up the page, I've now found yet another version of it. Not sure if it's the same one rebranded but the original one I posted the link to claimed 40 lumens and this latest one from Tioga is only claiming 15 lumens (run times are same for both)

Tioga RC100 Ruby 15 Lumens USB Rechargeable Rear Light 2014

A white front version is also available but claims 40 lumens

Tioga DC100 Diamond 40 Lumens USB Rechargeable Front Light 2014