Heat & Bond Medium Fusible Interfacing
What You Get+-
This is the interfacing that seamstresses use for stabilizing shirt collars and buttonholes - but I use it to back light colored fabrics so darker, more patterns fabrics don't show through them when I use them for applique. (You can see a video showing how I use it here.)
It's especially helpful in keeping white google eyes really white. :-)
This is NOT fusible adhesive. Fusible adhesive is just glue - used to stick two layers of fabric together. I use it for all my applique and you can get it here.
This is fusible INTERFACING. It's a sheer layer of fabric with fusible glue on one side. When you fuse it to your applique fabric, it fuses the sheer white fabric to the back of whatever other fabric you're using. If you want to then applique that piece to another piece of fabric, that's where you need to use fusible adhesive in addition to the fusible interfacing.
One package includes a 20 inch x 1 yard sheet of fusible interfacing - enough for hundreds of googly monster eyes. :-)