Single bubble; Scratch freeHigh optical clarity materialPrecision machined internal radiusBlack lines, internally fitted gives minimal parallax errors These level vials are Perfect for adding to all stationary equipment that can be leveled, such as stoves, refrigerators, washing machines, milling equipment, refrigeration equipment, heat pumps, furnaces, handlers, campers and any tool, device or object where level is important. Add one to many of your hand tools to know when you are working at level. These level vials are more durable than most level vials built into hand tools, they are made thicker and stronger.Brand new and high quality No glue or adhesive is includedSize: 10*10*29mmMaterial: AcrylicColor: greenWeight: 28g(10 pcs)Package included:4 x Square Bubble LevelNote: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.