The blue Silhouette Fabric Blade can be used to cut fabric in any of the CAMEO models, the Portrait and the Curio. To adjust the blade, use the gray ratchet that came with the blade or the built in ratchet on the actual Silhouette machine. Just insert the tip of the blade and twist.  When inserted and locked into the machine, the fin on the blade's housing should be pointing to 6 o'clock.The blue fabric blade should only be used to cut fabric. The fabric blade is exactly the same as the black ratchet blade with the exception of the casing. It is simply in a blue housing so it can be easily distinguished and used exclusively for fabric.