i think they come in 6/6 8/8 and 8/6 (f/r) so i am not sure it is ok to assume anything.
www.sigsauer.com

X-RAY3 Day/Night Sights
3-Dot Tritium System for superior glowing illumination in low-light.

SigTalk is a forum community dedicated to SIG Sauer enthusiasts. Come join the discussion about Sig Sauer pistols and rifles, optics, hunting, gunsmithing, styles, reviews, accessories, classifieds, and more!
It was only produced in 9mm.What caliber is the firearm? Different calibers have different combinations of f/r Sight numbers.
Right now you can send the gun to sig and for $119.99 plus ($55 shipping for any number of guns) they will replace all springs, clean all components and replaced any needed small parts and install XRAY 3 sights for you. Probably worth it to have them do it especially if you want it on at least 2 pistols....