For this price, this package can't be beat. Come assembled, and include anti-fog mirror lenses, rubber nosepiece, string nosepiece, rubber strap, bungee strap - everything you will ever need.
The fit is adjusted by adjusting the nosepiece and the strap. Tighter nosepiece - goggles tighter to the nose. Tighter straps - goggles looser to the nose. If both nosepiece and straps are tight, then there is more pressure holding the goggles to the face. Also, the angle of how they sit on the face matters. For me, it's best to push the upper inner corner closer to the nose, upward and inward. The fit is a bit weird at first, but surprisingly comfortable after about 3-4 swims, and no water leaks in.
Mine did need a slight modification - sanding the top and bottom edge of the goggle, because it had slightly sharp points (I think the Malmsten have the sharp points on the inner edge). Another point is that these are quite dark for indoor pools, and it takes a bit for the eyes to adjust to the low light.
Overall these are great goggles in a great package at a great price, and I will use them until they break (don't see that happening anytime soon). I will never buy another $15 pair of Speedo or TYR after using these. But I bought them instead of the originals only because of the low price, and to try them out. When they do break, I will definitely buy Malmsten to support their great invention, and suggest everyone else do the same.