197.312—Breathing supply hoses.
        
        (ii) 
         The pressure equivalent of the maximum depth of the dive relative to the supply source plus 100 psig;
    
    
    
    
    
    
        
        (iii) 
         Have a maximum working pressure that is at least equal to the maximum working pressure of the hose to which they are attached; and
    
    
    
    
    
    
    
        
        (2) 
         Be marked from the diver or open bell end in 10-foot intervals to 100 feet and in 50-foot intervals thereafter.