38mm (1.5'') Ban-Rol Super-Stretch Waistband Elastic

No Roll and No Crush waistband elastic.

Latex-free

46% nylon, 29% spandex, 25% polyester

From Threads Magazine:

The sewing professional’s favorite techniques

San Francisco sewing luminary Sandra Betzina uses Ban-rol XL-90 super-stretch elastic almost exclusively in her elastic waistbands, choosing a width compatible with her fabric type. This mesh-like elastic, which comes 3/4 inch to 1-1/2 inches wide, is available in white only and is sold by the yard off the roll (see Waistband supplies by mail). She cuts the elastic based on her waist measurement minus 4 in. and feeds it through a casing using a safety pin. Next, she uses a 75/11HS ballpoint needle to sew several parallel rows of topstitching through the fabric casing and elastic. What looks like separate rows of elastic fed through several casings is actually one complete band that does not roll, crush, or curl.

https://www.threadsmagazine.com/2008/11/01/the-great-elastic-waistband