..just like the original.
The band for the AR2078 and the QB78D is metal, but both of those rifles use a slightly larger diameter barrel so their metal band isn't an easy fit to a QB78. Could do it if you were (1) able to make a bushing (and plastic is perfectly accpetable in that use) and (2) slot the barrrel more deeply as the screw used is full diameter, not the thin reduced diameter one for the QB78.
Or just buy one of the custom made bands.