Ban-Roll -  2 yard, 5 yard or *10 yard Piece  1.25" wide
 
There actually are NO options for width - only 1.25". 
Banroll, Monofilament Stabilizer, Armoflexxx - they're all the same (in my book). 
First introduced to this product as "Armoflexxx" in Pants for Any Body by Palmer & Pletsch, I've used it in my dressmaking and all my own garments ever since. It bends with you, yet pops right back up for a crisp, clean, firm waistband. 
You can also use it in conjunction with elastic for part of your waistband for a bit of 'after-dinner growth". 
*FREE with 10 yard put-up:  Step-by-Step Directions for use as identified below.  
Complete step-by-step directions for using as a waistband stabilizer are available in PDF for $2 available at: 
https://www.londas-sewing.com/product-page/waistband-magic-crisp-waistbands-using-monofilament-stabilizer
 
See Video at:  https://youtu.be/ZV1bkV61JSA