Extremely high quality rail and carraige kit. Good heft, no wobbly, and a clean slide. It's such good quality and such a good price that I can't take away a star for an incorrect measurement in one of their pictures.One of the photos with dimensions lists the rail as being 2cm x 2cm. This is incorrect. The title of the product has the correct rail dimensions. "Happybuy Linear Rail 15-300mm..." The 15-300mm is correct as the rail is 15mm x 15mm x 300mm.If you don't need the rail to be 2cm x2cm, absolutely buy this item if you need a solid linear rail and carraige. This is the best one I've found in this price range on Amazon.
Noah 
