The CAME-TV Boltzen Fresnel Snap Kit makes modifying the Boltzen 30w and 55w fresnels quick and simple. With the fast magnetic adapter you can modify the diffusion, color temp, or add RGB effects. The kit is currently on sale from $128 to just $68 US. So why would this be better than just buying a dedicated RGB LED Light?
Well while the world is becoming more obsessive with RGB LED Lighting, one of the small problems with having this feature built in is that the maximum power for the light can be greatly reduced. As a rough example a 60 watt daylight LED is obviously a full 60 watts of power, and a 60 watt Bi-Color might be just 30 - 40 watts of brightness. When going to RGB, that same 60 watt light is even more greatly reduced.
What you'll find is some people will shop for a single color light that they most often use. This will allow you to get the smallest possible light with maximum output. Then in those rare cases where you would need the light color or temp to be modified, you can add gels. My personal preference is to choose a Daylight or Bi-Color LEDs as my primary key lights (as I often will use those on skin tones). Then for rim lighting, background lighting, or accent lighting, I'll work with RGB lights.
So while the current Boltzen 30w and 55w LED lights are not RGB, they are great portable fresnels (products here), and if you need a quick way of throwing on a splash of color, the Snap Kits are currently on sale (found here).