2 condition countif function using AND

i just saw a post where the op used
=COUNTIF(A$1:A$4,"<=0")*AND(COUNTIF(B$1:B$4,">=0"))
to count on 2 criteria. and sad to say i cant see how it works!
i'd use
=SUMPRODUCT((A1:A4<=0)*(B1:B4>=0)) to do the same.
its the use of the "and" thats thrown me whats the logic behind it.?

Hi,

=SUMPRODUCT((A1:A4<=0)*(B1:B4>=0)) to do the same

Not in all cases

All neg in column A, all pos in column B - same
All neg in column A, all neg in column B - same
All neg in column A, all neg in column B - same
All neg in column A, any pos in column B - different

*AND(COUNTIF(B$1:B$4,">=0")) this part just gives a TRUE or FALSE

The OP can just use

=COUNTIF(A$1:A$4,"<=0") to get the same result as

=COUNTIF(A$1:A$4,"<=0")*AND(COUNTIF(B$1:B$4,">=0"))

thanks i never actually tested the result without the *AND bit !
i assumed that it was some wierd formula that id never seen before!