No, the Laird was just a quick page grab to show the general idea. I don't recall any special instructions, but mine is located a foot away or so from the PC connector. It slides around pretty easily. The only markings I can see are "Fair-Rite V0" and it looks like Figure 2 on this page:
Round Cable Snap-Its Archives - Fair Rite
On edit: Mine measures about 1.25" long (C) x 0.42" high (D) which might narrow it down a bit. I didn't measure directly but it looks like the hole diameter is between 0.4 and 0.5 in. The PC cable is about 0.4-in OD and the ferrite slides easily on the cable.