Compatible with blades: CB09UB, CB09UB-K600.9mm Blade-holder with blue top, and brass tip / for 0.9mm CB09 blades. ATTENTION: If you are using CB09UA Blade (with spring); Insert only the CB09UA blade without the spring. This blade-holder, plunger design already includes an internal spring. These brass tip bladeholder, plungers are more rigid and lend to more accurate cuts.