The Stans No Tubes system was originally set up to allow riders with non tubeless rims and tyres to run tubeless. This system is still available as a set and many will benefit from this, but the sealant is also available separately. Stan’s sealant does exactly what it says on the tin, and does it surprisingly well. I have witnessed it seal pretty chunky gouges in tyres before. You should run some of this sealant when setting up any tubeless system as it will help keep you truly tubeless, rather than tubeless till a chunky thorn cuts through the bead and you have to revert to tubes again. Kind of defeats the whole object otherwise.