They are awesome, you do need a single 18650 cell (and a charger to go with). Size comparison with AA (left), 14650 (centre) and 18650 (right): http://www.dealextreme.com/customerp...2df98e8703.jpg

They also have a weaponized version....

You'll get 1 hour from a full beam, double on lower settings; bear in mind that a Maglite taking 3 Ds puts out only 77 lumens for comparison - modern LEDs are VERY bright.

If you want something that takes a AA (although lithium-ion cells are still better - whatever you do, do not buy regular NiMH cells - use eneloop-type NiMH cells or alkalines in an emergency), try this: http://www.dealextreme.com/details.dx/sku.28546. The Cree Q5 in this is about half as bright as the SSC P7, but it's 33% smaller.

For a keyring size, try this: http://www.dealextreme.com/details.dx/sku.13006

Very good quality, not nearly so bright, but long run time. You can see the tiny size here: http://www.youtube.com/watch?v=8EO5H1KsVYY With this size, very handy to take everywhere .