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Your picture is really too small to do much good, but I do know what they are.

I played a Miraphone 186 for several years that had presto linkage.

It is basically (as one might guess) a different type of linkage in which each of the valves paddles has it own spring that can be tightened via thumb screw to adjust the feel of the valves to whatever tension you are most comfortable with. I really do not know all of the industry jargon when it comes to tuba linkage parts, but I think you get the idea...

My primary teacher while I was in high school plays a great 188 (2-3 fifth valve length) with presto linkage, in other words, just like the one in the picture.

Just make sure you keep the linkage tight and well oiled. While it works very well, it has a tendency to be a little noisy if not well maintained.

My 186 came new with them in 1996, pretty shortly after they were introduced. I like them. It is cool to be able to dial them in to suit your preference. There is plenty of adjustment available. They will get noisy, though, if you reduce the spring tension far enough for the knurled knobs to back off from their seats. As for problems; the nylon rod ends will crack if you over tighten the wear-adjusting screw in the head, and also eventually from age. Your supplier should be able to get you spares to have on hand and that wold be prudent. (I keep two sets of these and the tools to replace them in a small "essentials" tool/part kit in the case.) The other concern I have with them is that the round rods that go from the flat plate that holds the knobs to the vertical members of the axle shaft support frame are only silver-soldered together. This being a perpendicular, butted joint with a tiny amount of solder makes it really susceptible to breakage if you use a gig bag much. I do and they did. I have a fix in progress for them utilizing two brass reinforcing pieces that I will post pics of when done.
One last thought: Normal valve oil is a bit light for the axle shaft. 3-in-1 works better. And keep an eye on the metric socket head (Allen) capscrews on the end of this shaft as they will back out from time to time. (The little hex wrench for these is also in my kit.)
Play well.

A fellow in community band complains about his cracked nylon rod ends. Is there anything besides OEM replacement rod ends that wear better and/or less expensive?