The Cowboy Studio detachable umbrella serves as a quick set up reflective umbrella. It also acts as a modifier for your light. The silver reflective material has a brightening effect, great for low light situations. Remove the silver/black backing and you've got a great shoot trough white umbrella that can help you diffuse your light instead. Available in various sizes to direct your light as needed, this umbrella is great for in studio and on location photo shoots.
Best of both worlds here: throws light (almost) like a silver umbrella, but softer. They are also an interesting convertible design, but I already have shoot-throughs I like so will probably leave the backing alone. Solid center rod and apparently well-built. My umbrellas always look banged up after 2 or 3 times out, but these are holding up very well.