I hope there not rubber. I don't belive they are either. There's no need since they're covered by the sleeves of her shirt. From the pics at SDCC they look plastic.
I must say I used to really fancy rubber arms and was willing to sacrifice articulation for aesthetics.... that is untill I heard all the horror stories about rubber arms, torsos etc.
I must confess, I used to think alot of the people who had issues with rubber arms or bodies that HT makes were either careless or playing around with their figures to much but after reciving my BSAA Chris and finally handling an HT piece with rubber arms, I must say I apologize for thinking that. While I've not expierenced any problem with BSAA Chris and hopefully never will (knock on wood) I must say I've worn condoms made of more duable rubber
. I'm afraid to pose the figure in any dramatic poses out of fear of the rubber cracking.