Replacing a servo case but I need something
 

I'm replacing a servo case for a Futaba S9301 case and I have everything to do it but as I was disassembling the case what looks like a black "O" ring broke off the top and bottom of the case.I tried finding some of them on Futabas website but their not on there.Anybody know where I can get some of them or if I go to my local hardware store what size do I need to get?Thanks to anyone that can help me out.

Danny Redd
(dreddbatfan)