http://www.amazon.com/Kyjen-2510-Carrier-Adjustabl...
I just ordered this for Lola as she doesn't walk on a leash and I like to take Cedric N Keylo on short hikes near my home. I haven't gotten it yet but from the reviews a med was best as she is 5.5 pounds and I want her to have enough space. I would bring him a sweater if you have one just incase it is a cool. Boot or his feet would depend on the terrain. if it is grassy/dirt type regular terrain I would say you might not need them. I would be sure to have a travel water bowl and fresh water for him....you know the basic stuff. I am sure others will chime in cause I have missed a lot I'm sure.
