Split after 2 months
I bought these with high expectations and they worked out perfectly for 2 months.  They don't get hot like the cloth and neoprene croakies.  I had them on a pair of costas, which have a thicker end, thus the XL.  However, after 2 months of use, normal use, I noticed that the end of the rubber grip had started to split.  Within a week it was split to the point that I was worried my sunglasses would fall out.  Oh well, live and learn.
Rating: 2 stars