The carriage blocks are of high quality - sturdy, with all deflections being within normal tolerances. The blocks I received were all black and silver, not the tricolor as you see in the listing. I was assured by the seller they are identical in everything but color.The packaging arrives in a padded envelope from China, with the bearings mounted on the rails, and in plastic bags. There is a ton of grease all over everything so be ready to wash the stuff first thing. You_l then want to pack with your bearing grease of choice. Also included are some plastic caps to cover the screw holes in an installed track, and plastic caps to retain the ball bearings in the blocks if you need to take them off the tracks.The only thing to note is that this rail profile is slightly different than standard thk 15mm rail - the shoulder on these is shorter, so these carriage blocks do not fit. Unfortunately this meant i could not use the bearings for my intended purpose, but will probably find an alternative use for them at some point.