With the kit I also got a blending brush free, which was lovely. I do have the Mac 217 but you can never have too many blending brushes.
The brushes are so densely packed I thought that they would absorb all the product, but they spread foundation so smoothly and give an amazing coverage, even with lightweight products like tinted moisturisers. The bristles are super soft and fine. I have found these brushes work really well with liquid foundations and cream brushes, but don't really seem work as well with powders.
So far my favourite brush has been the F80 and the F84, the only one I don't really use at all is the pointed F86 because I don't really get what its for. If anyone's got any tips leave a comment below.
When you wash these brushes you have to be careful not to use too much shampoo as they lather up alot and hold the product in the bristles.
If anyones looking for a great brush to quickly and flawlessly apply foundation I would really recommend the F80 and the F84 its just annoying that sigma is so hard to get hold of in the UK.