Lightskin

Thanks to S and P I have just received a Lightskin seat post.  This incorporates a set of multi-function LEDs directly into, and flush with, the seat post itself.  The batteries pop in at the bottom of the tube.  Perfect for my folding bike where external lights are a pain.  Currently I can only find this for sale in Singapore for 33.9mm, but there were some other sizes on ebay.