IRD RollerDrive 1 Inch Threaded Headset - Silver

I recommend this product

Have a very nice old custom 531 frame which however has always had to my feel slightly tricky steering. Including one memory of a speed wobble and generally never having been able to ride the bike no hands.
The old headset being well and truly worn out and noting the various claims of roller bearings as being an anti-shimmy measure, I got this one. Steering immediately feels much better. Steadier and smooth at low speed where it was always strangest and I think that made me not trust it when going faster. Will test it out on a proper hilly ride with fast bits soon but first impression is very much that the anti-shimmy claims were right.