And some of mine. The long 'Anquetil' ones were made by TA and they also made a short version. The length was supposed to help stiffen the shoe. Supplied complete with nails and a surprisingly high price tag for the day.
The alloy one is 'Pavarin' probably dating from the early 80's. I have the pair - but can't see me using them! Just a part of my 'What We had to Put Up With' black museum.
The black one is also 'Pavarin' but in a hard plastic and is possibly one of the first adjustable designs. There is a small plate that was nailed to the shoe sole and then the plastic slotted part was attached by small bolts to allow a degree of angle adjustment. I think they improved this in later models (which were also made in alloy) by making the back-plate a lot larger.
This idea then developed into the 'integral' adjustable plate such as the one shown on my 'Rivat' retro leather shoes. This was - at the time - a great leap forward and was a luxury compared to earlier designs. Trouble was that each shoe maker had a different design and very few - if any - were compatible.
Then we get into the minefield that is 'Clipless'............................
Today is the yesterday of tomorrow.