From the MAC website:
Sculpt and Shape Powder
A duo-pan shaded compact featuring a contour and a highlight powder in shades selected to complement each other. Professional formula. Jet-milled, ultra-smooth to apply: provides almost imperceptible shading. Use to shape and define the facial planes, or define the shape of the eye.
Bone Beige/Emphasize Palest Cream/Tan
Accentuate/Sculpt Pale blushed beige/soft taupe brown
Lightsweep/Shader Soft peachy beige/mid-tone leathery brown
Warm Light/Definitive Clean peach/mid-tone reddish brown
138 tapered face brush
A domed brush of ultra-soft, natural fibres featuring a slightly pointed tip with round chiselled sides. Specially designed to streamline and enhance the makeup technique of sculpting and shaping. Use chiselled side for contour shaping of facial planes; the pointed tip for applying and blending powder blush, highlighter or face powder.
169 angled brush
Synthetic, angled for precision, this brush is specially designed for the application/blending of face or cheek product.
223 tapered eye blending brush
Synthetic, tube-shaped with tapered tip, this brush is specially designed for the application/blending of face or eye product.
I've been hearing fabulous raves about the new Sculpt and Shape split pan powders, as well as the awesome rosebud-shaped 138 brush. This is one of the prettiest brushes I've seen. When I went to the counter to test-drive these, I was blown away by the breathtaking, gorgeous brushes. The 138 is the answer to my quest for a holy grail contour brush. The head is not too small nor too large, and is just perfect to do contour work. The sides of the brush are perfect for sculpting the cheeks, while the flowering tip doubles as a powder/skinfinish applicator. I bought the Accentuate/Sculpt duo as well and together, they work magic. In real life, the Sculpt powder really makes the face look more chiselled when used together with the 138, but unlike regular angled brushes, the 138's effect is neither too harsh nor too fake. The contouring looks really natural, so much so that it is hard to capture in pictures. The accolades of many reviewers online attest to the duo's effectivity, however.
I also got the 223 brush for my eye crease work. I am beginning to really, really love my 222 brushes (I can't do my eyes now without these awesome tools), but the 223 called out to me as well. The tapered head is a bit longer than the 222, but still tapered which is perfect for blending the eyeshadows together or for contouring the crease area. I just love these brushes. I am inclined to get the 169 as well because I just can't get over how pretty (and how useful!) these brushes are. Of course, these are quite high-end brushes (the 138, at $52 a pop, is one of the most expensive makeup brushes I own). However, most of the people who own MAC brushes really do attest to their beautiful craftsmanship and quality, and I am inclined to agree, especially with regard to the full-size brushes. MAC tools are indeed a wise investment, because these give you years of enjoyment and flawless application.