Checking to see if anyone recalls the size for the locking pin that accompanies the QR1 or the older P1 wheels. I have a feeling I am going to need one in about four days and I cannot locate mine.
Digging around through the CSL Elite wheelbase manual, the old CSL Elite P1 wheel rim had an M6 x 18mm bolt. Look at the top of page 13 on this PDF...
On the following page, you'll see that the pin and Allen key are to secure the P1 to the wheel bases quick release.