Broadfix Pro 1000x Small U Shim 1mm Yellow (55mm x 43mm x 1mm) U-SM1-B200 Applications Backpacker packing shims are used in hundreds of different applications in construction and DIY projects. These rot proof, water proof packers are used for levelling of battens, timber subframes, installation of door and window frames, drylining, levelling of kitchen and bathroom furniture, counter tops, sanitary ware, decking, garden buildings, first and second fix joinery and countless other situations requiring shimming, packing or levelling.