This weighs nothing and slides smoothly. There's a lot you can do with a 40cm slider.
I mount a ball head on the top and it lives permanently on top of my tripod (It's also handy to move the camera slightly back and forth to fine tune it's balance on the tripod head).
I even use it on news jobs, where I'm run and gun, as it adds almost no weight or size, but means I can instantly run off a tracking shot any time I like.