The N17 was replaced by the similar N57 and N77 from the mid-1970s notably the option of a ski brake just behind the toe binding .
The mid-1970s was improved in a number of minor ways .
The N17 was replaced by the similar N57 and N77 from the mid-1970s , which was improved in a number of minor ways , notably the option of a ski brake just behind the toe binding .