The Globe and Mail reports in its Friday edition that hundreds of Canadian manufacturers are facing a potentially devastating increase in tariffs after a change in how the United States applies metal duties to manufactured goods. The Globe's Mark Rendell and Jason Kirby write that starting on April 6, the U.S. began to levy a 25-per-cent tariff on the entire value of imported "derivative" goods made of steel, aluminum and copper -- a category that includes hundreds of products, from industrial equipment to household appliances. Previously, it had applied a 50-per-cent tariff to derivative goods, but only on the value of the metal inside the product, which often accounts for a small portion of the total value. This change applies to all countries, with a partial carveout for Britain. The change largely flew under the radar until this week, when Quebec snowmobile maker BRP suspended its financial forecast and said it could take a hit in excess of $500-million this fiscal year because of the metal tariff amendment. Dennis Darby at the industry group Canadian Manufacturers and Exporters said he has heard from companies over the past two weeks which are staring down a tenfold increase in their effective tariff rate.