Sorry for the unopenable link. Probably has to do with the fact that the original is a .png and not a .jpg file. It shows the original Lowenstein "Wiggler" patent drawing of 1919 for what we think of as the old Starrett wiggler with the 3/8 shank and the propellering needle indicator.
Thanks to all who responded, above. I am aware of the 1/2" shank on the modern Starrett kick-out style wiggler with the conical indicator point. I happen to prefer the accuracy I get out of the needle type. It is fiddley, yes, and there is a learning curve, just as there is with some other "old" methods, such as bore diameter measurements with the telescoping T's, but I find it quite accurate in some manual jobs for spindle centration over the center of a tiny center pop or scribed 'x', or for running along a workpiece edge to ensure parallelism of milling when the table is moving L/R. Some, I know, find these needle wigglers frustrating.
My interest in increasing the 3/8 shank OD to 1/2 is to minimize collet swapouts in some milling operations. In the absence of an available commercial version, I plan to sleeve mine (as rklopp has suggested in #2 above).
-Marty-