LOL...it's not labeled at all...it's from my misc. bin. Feels like a M100 or M110. Certainly not a M85!
It's actually the second "M110" I tried. The original spring was a Madbull dark blue (which is a M110 I think). Thank you for mentioning it though...I had forgotten the previous spring until you asked.
Both springs "felt" the same...or very close.