The "Peugeot insert" (also called the key blade, emergency key, or mechanical insert) is the metal key part inside a Peugeot key fob/shell.
What It Is
It is the physical metal blade (uncut or pre-cut) that inserts into the ignition cylinder (Neiman) to manually start the car.
Peugeot key fobs (remote shells) are often "empty shells" or replacement cases. You transfer the electronics (circuit board, transponder chip/immobilizer, battery) from your old key into the new shell.
The insert/ blade provides the mechanical backup if the remote fails or the battery dies.