How to using 2 conversion

hi all user dynamics

i’m marshell, i’m still new for ax 04. i have a problem for using 2 conversion for fabric. here my case

when we purchase we using: 1 roll.

in inventory, we use meter

in bom version, we use pcs.

So, how to make conversion from 1 roll tobe pcs? and would you explain for the impact for the stock?