there is a difference between a paper-back fusable web and an interfacing...fusable or not. fusable interfacing is only fusable on one side...not both sides. non-wovens are usually used on non-woven fabrics (knits) woven interfacing is used to stablize woven fabrics. there are different weights of interfacing, which one to use depends on the purpose and hopeful outcome. there are very lightweight ones, used for light weight fabrics (like silks) and there are really heavy-stiff interfacings like timtex (which is the same stuff used in baseball cap brims.) and everything inbetween. some people like to use fusable fleece in their bags/totes. it adds body/loft without stiffness.