Yes you can pledge the double of the amount, adding the shipping cost (the shipping cost stay the same as for the single one) and get 2 set of WingLights Carbon Black Edition. This is limited to 2 per backer.
WingLights use a couple of CR2032 batteries. They are not rechargeable but they are easily replaceable. The batteries will last roughly 3 months considering the average usage as a turning indicator light (10-20 seconds per curve in an average cycling commuter day). If the campaign will be successful in the second half of the next year we will be focused on a USB rechargeable version.
In the next 6 months we will work on a new mounter version which will fit the drop and cruiser bars, so follow us on twitter @cyclbike and on our facebook page https://www.facebook.com/CyclBike?ref=hl to stay updated and do not miss WingLights also for your bike!
Don't see the answer to your question? Ask the project creator directly.