As they are made from plastic they will not swell, shrink or rot, they are completely waterproof.

Features:

• Capable of withstanding higher compressive loads than traditional timber flat packers. This also makes them more economical
• They are colour coded depending on size, for easy identification
• The ever popular U-Shim is perfect for shimming behind a screw or fixing - Loosely install the fixing and then smply slide the required number of U-Shims over the fixing
• The unique comb/clip prevents the U-Shims from falling out, which leaves both hands free to tighten up the fixing