My Kessler Pocket Dolly Slider arrived last week. Several 5dmk2 + Dolly clips followed.

5dmk2, Canon 50 mm F1.4 @ F2 for audio clip
Nikon 35 mm F1.4 @ 2.8 for room clips
Tamron Macro Zoom 28 to 200 F3.5 - 6.3 @ 35 to 50 mm for vehicle clips.

Design and engineering, first rate. A stable free running camera carriage has transport options, push/pull, hand wheel crank drive via a silent rubber belt, or a line cord around hand wheel groove.

To maximize quick mount for 5dmk2, rotated 90 deg. adding a cardboard shim, allowing working clearance for the Nip lever.