Metal kidneys

*D1,*D2,*D3,*D5,*D8 are  made from blue steel and are more susceptible to rust. They are more rigid than the stainless steel kidneys.* denotes serrated ends.
D9,D1D4,D5A,D6,D7,D10 are made of stainless steel and are very flexible (except D10 which is quite thick and rigid) & won't rust.