Here I bought Philips Marathon Super Long Life 20W Dimmable Flood light. The CFL lamp is long gone, but I saved the box and the reflector that I recycle for the regular Philip Marathon SLS CFL lamp I have bought and used as described at Philips Marathon Super Long Life Universal 15W.
As you noticed the lens has been discolored by regular use. Some of my other reflector lens actually popped off by itself due to the age.
I'll continue to use the reflector part in the future uses. Of course if I planned to buy 25W version of SLS lamp, I would use that with popped lens as well.