Peugeot was a major user of Simplex DOs. I am most familiar with the version that has the cylindrical plastic insert to hold the axle position adjusting screws from the 80's and early 90's (I dunno, but there seems to be something about "Delrin" plastic that Simplex was really into it). Otherwise, Many other French makers used Simplex DOs but Peugeot might be the biggest of them. Good thing is, I never really heard of any problems with Simplex DOs, as you might with other brands cracking (I think some Suntour made DOs did that??). Simplex DOs might look plain and simple, but they do stand up to hard use very well.

Chombi