Feature: 1. Graduated Accuracy: The product consists of a accuracy caliper with two plates which overlap a portion of the length. The bottom plate is calibrated in millimeters and the top plate is transparent and marked with a cross shaped thin line cursor. 2. Testing Table: Crack monitoring gauges are used to control cracks in walls and how they evolve over the measurement time. Prime polymer with easy to read measurement grating. 3. Fixed Post: The redesigned fixing posts make it easy to fix the two pieces together without the need for glue. 4. Easy to Record: Provide a crack record sheet and secure with screws. The opening or closing of the crack can then be recorded on the record sheet. 5. Lightweight and Convenient: The product is made of prime acrylic plate is small and easy to carry, lightweight and easy to use. Specification: Item Type: Crack Monitor Product Material: Acrylic Use: Measuring Instrument Weight: 36g / 1.27oz. Package List: 2 x Crack Monitor 4 x Expansion Tube4 x Screws1 x Instruction Manual