Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: What is the weight capacity of this head??
Document: I purchased this to mount a D300 with 70-200 f2.8 VR zoom on a Bogen 679 monopod. The camera and lens are of substantial weight and I was worried that the head might not be able to handle the weight of the camera. It's rated for a 5.5lb capacity. My camera with the lens and MB-D10 weighs a beefy 6lbs 10oz, so I'm overtaxing it. If I was a working pro, I'd want something more substantial.
Typical Manfrotto, a superb design and manufactured to the highest quality. This is a lightweight head that easily supports double the rated weight. I am a pro photographer shooting birds in the tropics and cannot fault the product.
I was looking for a small tripod head to mount a decent weight camera (5-6lbs) to the end of an arm, which was in turn attached to the actor. It needed to be fairly light  but still hold the camera steady. It worked great and is very solid.
Only 5.5 pounds (2.5 kg). That is barely a camera body and lens. Mounting a telephoto on this actually feels like it might stress the head to the point of breaking because you'll come within a pound of the weight limit or exceed it if you're using any professional glass. And with shorter focal lengths, a monopod isn't necessary unless doing HDR work.
I like how this monopod head can be set at a certain tension and it works more or less fluidly with the camera mounted on top of it. If you set the knob at a critical strength based on your camera and lens combo weight, you can then tilt the head back and forth without any more fiddling with the knob and the whole setup stays that way. This is very convenient for a fast paced working situation.
The Manfrotto 234RC is amazingly solid and well-built, made from very thick metal. If you are looking for something light-weight, then this is NOT the monopod head for you. However, if you are looking for something that will last forever and hold your expensive camera gear securely, this is the one. Its very easy to pop your camera gear on and off the head with the quick release, which I really like for sports photography.
It has no problem handling the weight of my camera, although I'm careful with it just in case. For most folks taking photos of kids at various outdoor sports, this is the perfect solution. I can't imagine using a monopod without it. The head swivels 90 degrees for vertically composed shots. The locking quick release allows for fast removal of the camera for hand held shots.
The quick release plate supplied with the head has arrows that point in the direction that the lens is looking, but these are cast into the plate and hard to see when out in the field shooting. I traced over the markings with a Sharpie.The quick release mechanism is convenient to operate. It takes only a second to snap the camera on or off. The connection seems secure for a DSLR with a moderate weight lens.The major parts of the head are robust castings.
Great solid head for my Manfrotto Monopod. Fits perfectly on my Manfrotto MMC3-01 Compact 5 Section Aluminum Monopod for taking pictures or movies. This really takes the weight off your hands for those long movie shots without taking much space aroung people as a regular tripod would. The quick release mount makes it easy to attach your camera.
A bought a travel monopod, lightweight and strong. The first head I ordered came in at nearly 2.5 lbs. Ridiculous. Then I bought this little guy. It's perfect for a travel monopod (or tripod). More than beefy enough for my Nikon, even with 80-300mm lens.Part of the weight savings was because it didn't have extraneous features like panning which doesn't make sense for a monopod.
Answer: Manfrotto says 5.51 lbs.  I have personally put close to 8 lbs with no problem.