The Fenix L1P is a AA sized light. The Fenix L0P is a AAA sized light. The Fenix L2P is a 2AA light.
CPF member 4sevens has Fenix threads selling the series.
I have two L0P's on order and have given several L1P's and a L2P as gifts. Fantastic lights IMHO for the money spent.
Fenix L0P
Fenix L1P
I find the Fenix L1P to be too big for keychain carry. I will see how the Fenix L0P is in size when I get it. I will even take some pictures for you (Arc AAA, Fenix L0P, and L1P.)
The issue between the Fenix L0P and Arc AAA is runtime. The Arc AAA will run longer due to being a 5mm (driven too hard IMHO) vs. the L0P's LuxI. I don't use my keychain light often so I am going to go for a Endeavour CR2 Ion which is powered by a CR2 battery running a Cree 8mm LED.
Arc AAA ~$40 for the Premium model and the Fenix L0P is $47.95. The Endeavour CR2 Ion in HA BK/NAT is $145. The Arc AAA and Fenix L0P seem to be comparably prices with the CR2 Ion being a whole different animal.
I am tired of my Arc AAA Limited Edition. It was a great light ~2 1/2 years ago. Now I find that I dislike more and more and want to change it out as soon as budget allows for it. The color of my Arc AAA LE is cat urine green mixed with school bus yellow, not a nice color at all, possibly the LEd being driven so hard its past its 1/2 life. I get about ~11 lux out of the Arc AAA.
Another option now I think about it is the Peak Matterhorn 3 LED.
Peak LED
The lux reading off of the Matterhorn AAA with 3 snow white LED's was ~47. More than 3X that of the Arc AAA. Its not even the brightness, its the color, white as snow.
I stuck the Arc head onto the Peak Matterhorn body and it worked. The same goes for the Matterhorn head onto the Arc AAA body, but the Peak head was bigger than the Arc body and the Peak body was larger than ther Arc head, a mis-match IMHO.
You can always just get another Arc AAA. But there are new contenders in the AAA market, used to be just Arc AAA vs. Mag-lite Solitaire.