Nitecore is consistently reinventing their own products. They've done away with the HC90 and the HC50. Here is the HC60 - the newest and most efficient headlamp model that Nitecore offers.
Battery: 1 Lithium; Light Features: LED l Rechargeable l Batteries Included l Strobe l SOS Strobe l Water Resistant l High: 1000 Lumens for 1h l Medium: 210 Lumens for 7h 15m l Low: 1 Lumens for 680h; Other Info: CREE XM-L2 U2 LED. USB rechargeable with included cable. 117m beam distance. Impact resistant. Single button switch. Five brightness levels and three special modes. 100Á beam angle. Rugged PC material and aero-grade aluminum alloy. Chafe-free and breathable nylon headband.