Needed a precise distance control for my macro setup, so I was super excited to get this. On paper, sounded exactly what I needed. I have the Olympus 60mm f2.8 macro lens and the depth of field on that lens is so thin, it often miss my focus. With this Neewer focusing rail slider, I have much better control.The good:Does exactly what it says on the box. Love the fine precise control of the depth. This product nails it perfectly. The built quality is very nice. Feels solid and well-weighted. Also love the versatility of the arca mounts. Making camera changes a super simple chore. The etched markers on the rails are much appreciated too, which makes repeating the setup or adjustments just a little bit easier and more convenient to do.The not so good:Speaking of the etched markers on the rails, they are not dead accurate, but it’s very close. At least not on my example I have. Just be aware of it if you need super dead-on precision for whatever reason or subject you’re taking photos of.The sliding rails move very smoothly without the weight of the camera, but once it’s all mounted on the tripod, the cantilever design of the rails causes the movement to become very jerky and rough as you turn the adjustment knobs due to the weight of the camera and lens. Not a huge deal as it still works fine, but the jerky action does take away that quality feel and your perception of a precisely engineered product.This last complaint bugged me the most - Neewer applied way way too much grease/ oil on the rails!! The whole product was pretty much greased up with my finger prints after not realising the greasy rails and gears. I understand you need some for a smoother action, but please check out my photos. It literally is thick and heavily applied. I had to clean and wipe down the whole product with alcohol. Why?? Because I had to after getting the greasy oils on my camera controls, display, and lens!! You can’t just wipe it off with your hands or lens cloth, because it keeps coming back from general handling of the product. Absolutely stupid and unnecessary. Seriously, I was planning on dissembling the entire product to give it a proper cleaning, but seemed fine after a wipe down.Should you get one:At this price point, this is a good handy product and works exactly as it should. Just be aware of the cantilevered design if you are mounting a heavier setup, as it will cause the rails to slide rough and jerky. Not a big deal if you can see pass this minor shortcoming. Every time I move the rails, the jerkiness does remind me of using a low-budget product. Still, I doubt this would cause any long-term reliability issue to the movement, but I can see why Neewer applied a ton of grease to minimise this design disadvantage.As for the greasy oily rails, just be prepared to wipe down the whole product with alcohol after receiving it, so you don’t start transferring grease to your camera equipment and /or worse, to the subject you are taking photos of.