old hat

be an old hat at sth ( do something well, do it effortlessly.) — отлично разбираться, собаку съесть

Example: Give it to Brad. He’s an old hat with computers. He can do it in his sleep.

do it in one's sleep. — с закрытыми глазами сделать; разбуди его — сделает
Example: Give it to Thomas. He’s an old hat with cameras.

“ an old hat.” can also mean something old fashioned and out of date.
Example: Windows 3.1 is so old hat. Nobody uses it anymore.

Context is important.
Frequency of usage: rarely for both


know the ropes
know one's stuff
know the [ins and outs]
know sth inside out
[know one's onions]
[know every trick in the book]
know a thing or two (informal)
знать как свои пять пальцев
собаку съесть