If it's a sled that I plan to use a lot I used to use the MicroJig Zero Play bars.

On a 45* sled I made on the cheap for my Right tilting General 350 I bought a pair on Amazon, Chinese made, Aluminum, fully adjustable, ball bearing, and measured at 300 MM. They were cheeep, and actually worked quite well. I loved the name, Estink. I laughed about that for a while. The Zon must have been selling a bunch of them, they got to me next day, even though they said 2, 3 days. I would seriously buy them again. Beside price I don't see anything between them and the MicroJig sliders. Actually the MicroJig are flimsy until they are mounted, these were rigid, and quite easy to use.

The last quick jig I did was my 1/4" finger joint jig, and I cut out some QS WO and fit them using a shooting board, they remained stable and slick through all 4 seasons. Just only over a year old, so long term hasn't been decided.