Machined from 6al4v Titanium or 702 Zirconium, these are sized to fit the ZT0620/30/40 series of knives ONLY! *The "BLACK" color option changes the material to 702 Zirconium* The MONSTER Thumbdisk is 25% larger than the stock model, but without protruding past the scales. Drop in fit. This is THE answer to those hard to open knives! ***THIS ONLY FITS ZT0620/30/40 SERIES OF KNIVES!***