Then X-Men #139 gives him the brown-and-tan costume. The shoulder pieces and the stripes from the yellow outfit are gone. You've still got the pointed mask, the boots, the expos…

Then X-Men #139 gives him the brown-and-tan costume. The shoulder pieces and the stripes from the yellow outfit are gone. You've still got the pointed mask, the boots, the exposed arms and the same short, heavily built guy underneath it. It changes quite a bit without making him unrecognizable. The larger brown areas make the design simpler, and the whole thing is less bright than the yellow and blue. Kurt asks about the change and Logan's answer is basically why not. There isn't some massive event where the costume grants him a new ability. He just changes what he's wearing. Considering how much explanation superhero costume changes sometimes get, that is a pretty straightforward way to introduce a look that sticks around for years.