Mikmar make various versions of their bits, some are snaffle, some are shanked.
@newforest you are right a western shanked bit is used on a finished horse and by good hands.
The thing that is different is the mouthpiece, it's a cast mouthpiece with a port and roller. They're pretty chunky and wouldn't be suited to any horse without much space in the mouth.
I've seen them for sale but never heard or seen anyone using them, the original ones were very bulky (the sides were also cast and not very nice to look at) and also light so not suited to reining as it makes the aids a fuzzy.
Any bit with a tall narrow port is unsuitable for novices IMO, as you can do serious damage to the roof of the mouth with them handled improperly, they can be very severe. The results could be horrific if it were used with a noseband especially something like a flash that clamps the mouth shut and would exaggerate the leverage on the port. Like many bits when understood and used sympathetically they can be gentle but poorly understood and in bad hands they could be awful. You have to remember that many Americans consider severe bits to be novice bits, a 'shanked snaffle' is a prime example, when you understand the mechanics of it they are not gentle at all, but in the US it is a bit commonly used by novices and in bringing on young horses. You only have to look at the chain and twisted wire snaffle to know their not gentle but its just a snaffle so it must be suitable for novice hands right?