Kunio Onishi is the man behind this design and through winter he can often be found on the banks of the Tongariro. 
Usually found with a spey rod in his hand of which he is a master caster this is his “go to” fly. 
Tied on a Tiemco 708 with a blanced 40 ° bent shank it has a Keel fly profile which should help with more hooking and less snagging! 
 
Hook size 6, 8, 10

Per Dozen