The SeedJig has three main components, all precision machined in the UK:

817M40T steel, hardened and temperedAbsorbs the blows of the punch.
Provides location holes for indexer positioning- 2 for number, 8 for letters*
Indexer303 stainless SteelEvenly spaces the letter punch positions. The resulting embossed text is neat and legible for peace of mind.
Lockpin416 stainless SteelSecures the washer in place while it is being stamped. Acts as central pivot for the Indexer. Accepts m8 washers 1.5-2.5mm thick, 23-30mm Ø

*The longest word in BIP39 word list is eight letters. Only first four letters of each word need to be used.