By split into 2 groups, group 1, for example, a single mast is long (Stud) There are a number of 16 samples and samples with 2 mounting rails with steel Assembly screw on the CG (Track)
The research is divided into 2 group 1 single column long (Stud) were 16 samples and the samples that 2 consists of a steel rail screw into alignment CG (Track)