So okay now you know your Seiko takes a 1.1mm tipped spring bar, we are over that hurdle. But now you are having an issue getting Seiko Fat Bar's (or Toxic Fatties) threw the spring bar hole on your rubber/leather/canvas. What do you do??? Lube up the spring bar with some WD40/Astro Glide/or old fashion slobber??? Heck no you get you a pair for the Toxic Slimfats to save the day!!! Basically this is a spring bar that the middle section of it has been reduced, so instead of it being 2.5mm thick now it is 1.78mm thick. Wowsers!