I recently purchased a pair of 24" Bessey K-Body REVO clamps. I have quite a few K-Bodies but I wanted to add the new version for the angle head jaw capability. If you are familiar with the original K-Body then you already now the basics of these great parallel clamps.
The Revo has a larger jaw surface area as shown in the comparison pics below. It is a fairly significant increase. I think the added reach on both the top and bottom side will be the most useful, but in general more surface area is good thing.
The new handle is larger and is very nice. It is no problem to get a lot of clamping force. You can really "feel" it tighten down as you turn it. I don't know how else to describe the feel but it is different than the old one. Maybe something else has changed in the body as well.

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The faces of the jaws are now removable. The back side of the stationary jaw has a face plate as well for use when spreading or it could simply provide a replacement if needed. However the faces are held in place by the slot corresponding to the shape of the bar. They sort of snap onto the bar when slid onto the jaw. Which means the one on the back side has nothing to grip and slides off everytime you grab the clamp on that end to pick it up. I plan to just leave it off.

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Each clamp also comes with two flat topped saddles that snap onto the bar and will support the work off the bar. This is a nice feature, it will help keep glue off the bar and also prevent the bar from damaging the work piece. The new and old bars are the same so the saddles as well as the moveable heads are interchangeable with the old K Bodies. Two saddles come with each REVO.
The REVOs also have a new tail piece. I like the old one better , it is easier to get on and off. However the new one provides a hole to put the hold down clamps through. The hold downs are the same as the ones designed for the Bessey WS3 and WS6 Angle Clamps. They can be put through the tail piece hole and the saddle hole to attach the clamp to a work surface. They open to 2". The holds down do not come with the REVO.
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When the REVOs are standing on the bench the bar is about 5/16" taller than the old K Bodies. This could be a nuissance when mixing the two for a panel glue up. Keeping the REVOs in the outside/end position should take care of it. If the saddle is added to the old and left off the new , then they are nearly the same height.
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OK now we get to the reason I bought a set of these. The variable angle jaw. These are slid onto the jaw in place of the standard face. They can be positioned at any height , in multiples , on the bottom , or even on the back side. They are about 7" long. And the face is slightly convex, not sure why. They are not included with the REVO.
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When I saw angle attachment I immediately thought of re-glueing chairs. And they are perfect for this type of situation.
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They can also be used to spread force along an edge. And will tighten when offset for some odd ball situation. I am sure they will come in handy in many applications.
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When set up for spreading the old K Body actually has the advantage in the minimum opening because the handle is shorter. The minimum opening for the REVO is 9 5/8". But both old and new K Bodies can be placed in a smaller opening by flipping the head to opposite side from the tail jaw. This will give a 7 1/2" with the old or about 8 1/2" minimum with the REVO. This can be even less, about 5", if the handle can be placed outside the workpiece.
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Overall this is a very nice clamp. The angle jaw alone makes it worth having. I could see the possibility of Bessey coming out with additional slide on jaws, for example one that would make it into a corner clamp.
There is also another version of the REVO called the REVO VARIO. It is the same except the tail jaw is also moveable.
I suspect at least a few more of these will be added to my collection.