Okay there isn't a ton of info out there so let me see if I can clear up some issues with this short blog. When picking a spring bar for your watch there are multiple things to consider.
1) The main thing is you want the tip of the spring bar to fit into your watch case lug hole correctly. If the spring bar tip is too small it can fatigue your watch case to the point it will damage the drilled lug hole. If the tip of the spring bar is too large then it won't fit into your lug holes so you can even use them.
2) You want the middle section of the spring bar to be the same size of your stock spring bars. Unless you have clearance issue and you need extra room for a strap (check out Toxic Curved spring bars also).
3) Double Flanges or shoulder-less spring bars? If you have a watch that has drilled holes all the way through the case then you need shoulder-less bars (it will work like a sold bar welded into your case). If the watch case has holes drilled on the inside of the lugs then you want double flanges for easy removal of the spring bars (these aren't always available for all sizes).
4) You need a good quality made spring bar that is either 304L or 316L, And a robust inner spring inside the spring bar so it won't prematurely fail.
If you have any questions then please let me know and I will try my best to found out the best solution for you.