Steel pedal expanders. Mine are from Risk I've seen them branded differently
Strongly recommend if you don't like having clean threads or skin on your knuckles. I thought the threads would still be fine but no, it took me an hour to remove them despite all the grease I used. Metal is very soft and bends when uninstalling, threads are toast after 1000km.
Thankfully the threads on my PM crankset are still okay. My look pedals were ruined so I'm gonna try the ultralight zeray pedals as a replacement. Hope I don't give an update from the hospital