"six feet six" or "six foot six" ?

[japanjapan]

Dear teachers,
Please look at the following sentence:
he has brown hair and he's six foot six.
I think the sentence is wrong, but I am not sure.
When we talk about people's height, should we use "foot" or "feet"?

Thanks

[Casiopea]

Dear teachers,
Please look at the following sentence:
he has brown hair and he's six foot six.
I think the sentence is wrong, but I am not sure.
When we talk about people's height, should we use "foot" or "feet"?

Thanks

six foot six is OK.