Would this be compatible?

[Caribou]

I looked around the forum, and this seemed like the best place to post this, so here goes:

I have A Cybergun Thompson M1A1, but only one magazine which it blows through pretty quickly.So I was looking at different magazines to buy, and noticed this one http://www.redwolfairsoft.com/redwolf/airsoft/Magazines_King_Arms_AEG_King_Arms_450_Rounds_Drum_Magazine_for_King_Arms_Thompson_Series_Black.htm

It says it's compatible with Tokyo Marui, but would it be compatible with my mine? I really want a drum mag, but dont want to buy one that dosent work with my weapon and I have to send back.