Kelim, Chapter Twenty-Three, Mishnah Five
1) A fishing net is susceptible to uncleanness on account of its bag.
2) Nets, snares, bird-traps, slings and fishermen’s skeins are susceptible to uncleanness.
3) A fish-trap, a bird-basket and a bird-cage are not susceptible to uncleanness.
Section one: The bottom part of a fish-net is sewn together like a bag. Therefore, it is susceptible to impurity.
Section two: All of these various types of traps are considered to be vessels and therefore they are susceptible to impurity.
Section three: In contrast, these types are not considered vessels and they are therefore pure.