U-POL ‘B’ polyester glass fibre filler is a two component chemical paste with glassfibre strands (chop strand mat) used for bridging of holes and rust in surfaces such as steel and GRP. U-POL ‘B’ forms a very hard, durable surface and can be sanded and shaped if required. It is easily covered with standard polyester filler or can be over-painted with most common paints.