From their site: The workday will never get you down in this elegant MBT.

PROFESSIONAL COLLECTION:

All MBT footwear features:
Wearing MBTs provides many pro-body benefits: this is the result of an increasing number of international studies supporting the numerous health benefits of the "anti-shoe".

Step. Rolling action. Step. Rolling action. This simple movement creates tremendous benefit. Helping solve knee ^1;2 and back problems,^3;4 relieve tension in the neck,⁵ ease joint pains^6;7 – and more or less in passing help to tone and shape firm buttocks and thighs.⁸ And burning more calories when standing⁹  and slow running¹⁰ compared to ordinary shoes.
The important thing is that every one of these claims stands up to scientific research - which is why the "anti-shoe" is now even prescribed by doctors and recommended by fitness experts.

1 Nigg et al. 2006 a
2 Andriacchi et al. 2008

3 Nigg et al. 2007

4 Jørgensen 2006

5 Smolenski et al. 2008

6 Vernon et al. 2004

7 Nigg et al 2006 b

8 Linde & Stegen 2005
9 Hoppeler et al. 2008
10 Müller 2007
[Sources]

Last: Semi-curved