DMKAL,
Not sure about the "Fender Pack Advertized Above", however, the stock fender pack is big enough to house a small first aid kit, only if that is all you wish to carry there. I ride with some people who use the fender pouch for a small tool kit and use some type of pack made by MSR that straps to the back of their chest protectors for 1st aid. We figured that this makes sense since usually you have to fish someone out of the trees or from a ditch to render first aid, if you couldn't get your bike to the "casualty" it would be tough to run back and forth with a handful of meds. Look for a fanny pack or the MSR pack, not sure how much they cost, but to be able to shuck a chest protector and start working as opposed to running for tape or a pressure dressing could save someone's life. Good luck and glad to hear that the RMX is doing fine!