This is a Creative Grids non slip quilting ruler. The markings include 60 and 45 degree angles which is helpful.
Gudrun Erla, creator of the Stripology rulers, shows you how to quickly cut your own pre-cuts.
Square Up Slotted Quilt Ruler Clear Patchwork Ruler Acrylic 3mm for Cutting Fabric Paper Quilting Sewing Craft Template - AliExpress
Creative Grids XL Stripology Ruler, Creative Grids #CGRGE1XL
Creative Grids Stripology Ruler
Creative Grids USA ®
Creative Grids Stripology XL Ruler, Acrylic - CGRGE1XL : Arts, Crafts & Sewing
Creative Grids Stripology Ruler
GE Designs Stripology 2 Book
Master Your Stripology Rulers Book
Quilting Tools & Equipment, Quilting, Sewing, Crafts - PicClick
The Stripology Squared, a slotted ruler by Gudrun Erla, has cutting slits every 1/2 inch so each strip you cut is the exact same size EVERY time!
Creative Grids Stripology Squared Quilt Ruler - CGRGE2
Creative Grids USA ®