THE ETCHING TOOL: The Etching Tool fits in the blade housing unit in the Silhouette brand (ALL Models) and the Cricut brand electronic cutting machines (only these: Original, Expression, Expression 2, Create). Also fits: Wishblade, Zing, KNK, US Cutter, Gazelle, and Pazzles. It can be used to engrave & etch many materials, including acrylic, plastic, glass, metal, metal clay, leather. Materials used should sit on the machine’s mat and fit under the machine’s rollers. Although the tool theoretically could etch steel/stainless steel, the machines don’t provide enough pressure for success. Ensure the machine you use can accommodate the media you desire before committing to specific media use. PEN & MARKER HOLDERS: With the Chomas Creations adjustable Pen Holder, you can draw & sketch with up to a 3/8″ (inch) pen. With the adjustable Marker Holder, you can draw & sketch with up to a 1/2″ (inch) marker/pen. There are no height restrictions: simply add Pen or Marker Holder to your machine, adjust the height of your pen/marker with the provided craft stick, tighten the screw (made of durable plastic) and you are set to draw & sketch! The markers you use may not be centered in the Marker Holder. This does not stop them from drawing, it just means you won’t be able to draw and then cut a shadow perfectly around the drawn design. Note before ordering: Works with the Cricut machines EXCEPT the Cricut Explore models (Explore, Explore Air, Explore Air 2, Explore ONE) and the MAKER. THE ALUMINUM BLANKS: This bundle includes two (2) anodized aluminum blanks for practicing metal etching (color: blue). Blank size: 3.50″ square (88.9 mm square) – Thickness: .016″ / 0.406 mm / 26 gauge. For best results, remove any oils from blanks by wiping them with alcohol and allow to dry before placing on machine’s mat. The blanks may be tumbled to remove burs after etching (30 minutes works well). PEN: Bundle also includes one (1) Sharpie Pen (color varies).