Review on Optimized Neewer 31.5-inch Motorized Camera Slider: Wireless Control, Carbon Fiber Track Rail with Silent Motor, Time Lapse Shot, Follow Focus Shot, 120° Panoramic Shot. Supports DSLRs with up to 22 lbs Load Capacity by Jeff Drollinger

This thing is great. I didn't want to spend more than $500 on a slider and did a little research before settling on the 2.4GHz version of Neewer as I didn't want my phone to be tethered to it. Many of the other inexpensive models have relatively high minimum speeds. This one I spotted took 1 hour and 6 minutes to run 18.5 inches at 1% speed settings! You need to roll or loop back and forth from a->b, b->a. When it approaches the set end stop, it slows down slowly so as not to jerk the camera. Really great unit. I recommend a very sturdy tripod if you use one to hold it. I use the Gitzo 4 series with BH55. You may also need a very long arc plate to hold it securely as a mounting hole can cause it to twist (18 inches from center * 4 lb camera, lens and ballhead = 6 ft lbs of torque) and at mount to a mirrorless . Don't be afraid to make this purchase, it's a great investment.