Natterhorn (ST251) sits mid-range in the Montane design at 25-29% light reflectance, the same as Rainier. It appears as a mid-tone taupe with straight grain and small knots in Armstrong's swatch, warmer than Rainier's gray.
Where Natterhorn meets a thicker resilient floor at a doorway or room edge, lay the thicker floor first. Then adhere a 12"-wide strip of scribing felt against it and feather the felt's edge down to the subfloor with S-194 or S-466 patch, so both floors meet at the same height. Don't run the planks across expansion or isolation joints in a concrete slab; use architect-specified expansion joint covers there.
Finish: Diamond 10 Technology
Installation and warranty: Full-spread glue-down. The 30-year commercial limited warranty requires a recommended Armstrong adhesive, such as S-995 or S-1000, installed according to Armstrong's instructions.