I'm not familiar with the movement, but I do like how they designed what I think is a balance-wheel guard into the balance cock. Longines 4LLV had an extra guard that I remember being a pain to replace the screws on. Being that these small movements are so hard to handle without a finger touching the balance and either stopping it or snapping a pivot, it's a good design. I can't say I like the looks of the Illinois design, but it does look functional. At least I think that's what the function is. Cheers.