Using

=SUMPRODUCT(B8:B16=B2)*(C8:C16=C2)*(D8:D16)

Where drop downs in:
B2 = uPVC
C2 = 160

And this row exists in the table B8:D16

uPVC 160 Class 16

Formula returns #value

Googled examples would have me believe "Class 16" should be returned.

Thanks.
Howard