I assume that you mean the (mainly) black plastic clamps. Each half has a small dowel part that fits down into a single hole in the MFT3. It does not pertrude beyond the underside of the MFT3 but, when correctly used, they have a screw in knob that secures them in place. This knob screws in from underneath. Some people use them without the securing knob. In most cases that works well but the work piece can elevate a little as the clamp tends to buckle upwards. Failure to use the knob can, in the long term, ruin the shape of the hole in the MFT3.
Should you be considering other clamps for the MFT3 you need to consider that they all need plenty of room underneath in order to allow the right angle metal end to fit down and through the hole in the MFT3. You may also want to use then with the 'action end' beneath the MFT3 in which case you need even more room.
Peter