It is the blue speed roller.

There are now only two rope pulleys: The "red" TANDEM and the "grey/blue" TANDEM SPEED as available here at Galaxus. The TANDEM SPEED can still be used for steel cables. The stainless steel pulleys are important. However, Petzl is no longer allowed to write the use of the TANDEM SPEED for steel ropes in the instructions for use due to changes in the standards (waterproofness and finger protection - since September 2021). See Petzl under "Technical advice": "Using the TANDEM SPEED on a wire rope - https://www.petzl.com/DE...
The TANDEM SPEED pulley can therefore be used on wire rope without any problems.

Better too fast than too slow. If you go "too fast", you can (hopefully) brake with your gloves. Hence the "speed" variant. For rope and cable that would be "blue", but I can only find "grey" in the eShops and at Petzl, seems to be ok too, here is a video with yellow (bad) and grey (good) on a steel cable. https://www.youtube.com/watch
And for this ferrata, they also recommend the grey one with construction gloves: https://www.viaferrata-fr.net/via-ferrat...
I don't know any more than that.

To my knowledge, there are only 2 models
- red (normal)
- grey (speed)

Hello
There were 3 different Petzl Tandem pulleys. The red "Tadem" for textile ropes, the yellow "Tandem Cable" with hardened pulleys for steel ropes and the blue-grey "Tadem Speed" with hardened pulleys and ball bearings for all ropes (after steel ropes no longer use for textiles!)
Due to specifications in the area of steel ropes, the yellow "Tandem Cable" has no longer been produced since 2021 and the "Tandem Speed" is now only approved for textile ropes.
This is the blue-grey Tandem Speed.