International Divers of Montreal Canada made direct copies of US Divers regulators.  This single stage was a Mistral copy.  It retailed for $60.00 in 1958.  This model was located by the museum staff near the Toronto area.  The hoses were perished so new reproductions were placed on the reg.  This model did not use a duckbill instead opting for a one way valve lodged in the exhalation hose.