Because of some changes we made that make the QC2 holds much stronger than the originals, the QC2 holds are unfortunately not compatible with the original QC plates.
This has to do with the shape of the cavity on the back of the hold that seats the cleat on the plate (among other things.) The original QC holds had square shaped cavities that fit square shaped cleats. However, square shaped cavities have sharp corners that create high stress points which, under repeated use, are more likely to fracture. In fact this very problem plagued the airliner industry early on, and is why the windows in pressurized airplanes have rounded corners.
So we took a cue from the airline industry and essentially did the same thing - round the corners of the cavity. This greatly reduces the stress points of the corners and dramatically increases the number of cycles the holds can endure (we now stress test to well over 10,000 cycles!) However, this also means they will no longer fit square shaped cleats, so we had to round the corners of the cleats as well.
The conversion kit replaces the square cleats with rounded corner cleats. They will still fit the old square-cavity holds, though we recommend you replace them with the much higher strength QC2 holds if you are using them with higher weights and/or a lot of cycles. But they are required for all new QC2 holds as we no longer manufacture or support the original QC holds.
Switching out the plates is relatively easy and is demonstrated in the video here: QC2 Conversion Video
You essentially remove the two screws that mount the cleat to the plate using the 4mm hex key, being careful not to lose the spring embedded within. The screws are secured in place by threadlocker, so removing them will require a bit of torque. Then reattach the new cleats with the same screws, using a drop Loctite threadlocker on each screw to help ensure they stay secure.
The kit includes 1 or 2 cleats, depending on the desired quantity, a 4mm hex key, and a single-use packet of Loctite 242 threadlocker.
We apologize for the inconvenience for existing customers, however we feel the increased strength and endurance of the new QC2 holds are more than worth it.