Definition
Contributions are tax-deductible up to your annual contribution room (18% of prior-year earned income, capped). Growth is tax-deferred until withdrawal. The Canada-US tax treaty exempts U.S. dividends paid into an RRSP/RRIF from the 15% U.S. withholding tax (effectively no withholding applies).
Source
Income Tax Act; Canada-US Tax Treaty Article XVIII