As standard, a classic bag consists of four sides and a bottom or from the so-called length and two sides. In the case that the bag is sewn from a circular fabric, the body of the bag is formed by a circular fabric that can have reinforced belts, on which the carrying straps are sewn.
The construction of the seams can be as follows:
simple - the hem is only from one side of the seam, from the outside.
double (complete) dustproof - the seam is on both sides of the seam, on the body of the bag.
triple dustproof - is a tie, with the help of which the best sealing of the bag seam is achieved; three sealants are used, from the inside, outside of the seam and between the sewn fabrics. An 18x3 mm weft is inserted between the fabrics.
Possible design of the internal structure of the bag, which ensures that the shape is maintained even when filled: