One of my favorite LED headlamps is the Streamlight Argo HP. http://www.copquest.com/10-4775.jpg
I purchased mine about 3 or 4 years ago. After Hurricane Ike, I pulled it out to use it. It had not been used it in over a year, but it had been laying around the house on a shelf somewhere. The body had developed a crack in and along the bottom of the o-ring groove to the battery compartment. This prevented the battery compartment cap from making contact, thus the light no longer functioned. This type of failure leads me to say that there is a design flaw with this headlamp. The thickness of the plastic between the battery compartment and the bottom of the o-ring groove is probably about a millimeter or less. Maybe I should have kept some silicone on the threads and o-ring, as it probably broke when someone either tried to turn the battery cap, or unscrew it. The headlamp for its lightweight and small size, is one of the brightest around. I will be selling this headlamp really cheap in the near future. It could be super-glued shut, and used for a couple of hiking trips, but it wouldn't be reliable enough to take caving. I don't think duct tape would fix it. This lamp is less than $ 24 new at: http://www.brightguy.com/products/Streamlight_Argo_HP_Headlamp.php [ This is the older model with 33 lumens on high mode, and 12 lumens on low mode. ] A newer version alledges it uses a brighter C4 LED. [ 55 lumens on high mode; 18 lumens on low mode] David Locklear Additional reference: http://www.streamlight.com/product/product.aspx?pid=55 http://www.cheaperthandirt.com/16443-1.html http://www.amazon.com/Streamlight-61302-Headmount-Flashlight-Black/dp/B00081NHBA http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130257074972&category=106987&refid=store#ebayphotohosting
