Area-51m R2, 240W AC/DC adapter

Not quite 5 years ago I bought an Alienware Area-51m R2 laptop. On my 240W AC/DC adapter I have noticed that the "rubber" around the connection (where you can see the blue light) has started to fray abit. I don't want to wait until it completely breaks before I replace it. I was not able to find this adapter in the Dell on-line store under "Compatible parts and Upgrades". They only have the Dell 180W 7.4mm AC Adapter. Thanks in advance for your assistance.