I Googled: "Stick S25 umber bulb" and found a lot of hits.
I then found this video...
Which led me to this website: 1to8.net
They have lots of LED kits on their FB page.
Edit: Looks like you can order it here... http://www.studie.jp/bestitems/item/...ml?item_id=658
or maybe from these guys? http://dort.jp/company/index.html