What material are the stainless steel products you have made of?

You have to request, but as an example:
MPT series  Stud is made of 1.4305, spring is 1.4310, receptacle is 1.4043

The HHS series Stud is made of 1.4303 ; the pin is made of 1.4310K-4 ; the belleville washers 1.430 with a tensile strength of 1500-1700 N/mm²

in order to increase corrosion resistance in salt air environments such as marine conditions, the stainless steel has been passivated.

For example also the MTH series: MTHTLS-*S=   stud: 300 series cres; cup: 300 series cres; spring and crosspin: 302 cres
Fixed retaining washer: MTHWFS=   1.4310
MTHR25S is made of stainless steel 1.4825