Many here, myself included, purchased these stationary rollers last year--until they ran out of stock.
They're back on Crest's website for the same $36 price plus shipping that was available last year:
http://shop.crest-electronics....GE-4-PK-CRE50101.htm
They work great on Gargraves phantom tinplate and Lionel O gauge track.
Also, purchase and install 4 6-32 nuts for each roller section to provide stability--16 per package--the nuts provide a tight fit between the rails.
Just a heads up for those who may have missed out last year, or are now interested.