I always thought a zip was an oz ! Not 6 oz Am I wrong ?
Weed has always been sold in weights of Imperial ounces.
1/2 = Arfers
1/4 = a queue
1/8 = an 'enry (Henry the Eighth)
1/16 = a tina (sixteenth)
A nine bar = 9oz
It has always been that way and probably will not change. In UK anyway. However, small £10.00 deals are done by the gram! or nearly a gram.
Just my thruppence 'apenny. eP.