=IF(AND(B4="35mm x 125mm Skirting Duct",B9="BLACK"),"PL35125DB",IF(AND(B4="35mm x 125mm Skirting Duct",B9="WHITE"),"PL35125DW",IF(AND(B4="35mm x 125mm Skirting Duct",B9="OPAL GREY"),"PL35125DO",IF(AND(B4="35mm x 125mm Skirting Duct",B9="NATURAL ANODISED"),"PL35125DN",IF(AND(B4="35mm x 125mm Skirting Duct",B9="POWDERCOATED"),"PL35125DS","")))))

=IF(AND(B4="35mm x 150mm Skirting Duct",B9="BLACK"),"PL35150DB",IF(AND(B4="35mm x 150mm Skirting Duct",B9="WHITE"),"PL35150DW",IF(AND(B4="35mm x 150mm Skirting Duct",B9="OPAL GREY"),"PL35150DO",IF(AND(B4="35mm x 150mm Skirting Duct",B9="NATURAL ANODISED"),"PL35150DN",IF(AND(B4="35mm x 150mm Skirting Duct",B9="POWDERCOATED"),"PL35150DS","")))))

=IF(AND(B4="50mm x 150mm Skirting Duct",B9="BLACK"),"PL50150DB",IF(AND(B4="50mm x 150mm Skirting Duct",B9="WHITE"),"PL50150DW",IF(AND(B4="50mm x 150mm Skirting Duct",B9="OPAL GREY"),"PL50150DO",IF(AND(B4="50mm x 150mm Skirting Duct",B9="NATURAL ANODISED"),"PL50150DN",IF(AND(B4="50mm x 150mm Skirting Duct",B9="POWDERCOATED"),"PL50150DS","")))))

=IF(AND(B4="50mm x 200mm Skirting Duct",B9="BLACK"),"PL50200DB",IF(AND(B4="50mm x 200mm Skirting Duct",B9="WHITE"),"PL50200DW",IF(AND(B4="50mm x 200mm Skirting Duct",B9="OPAL GREY"),"PL50200DO",IF(AND(B4="50mm x 200mm Skirting Duct",B9="NATURAL ANODISED"),"PL50200DN",IF(AND(B4="50mm x 200mm Skirting Duct",B9="POWDERCOATED"),"PL50200DS","")))))

Idea's?