Kettlebells are brilliant for increasing strength, flexibility, core and general coordination . I like my female clients to work towards using a 12 kilo kettlebell. We often start with 4 kilos and gradually work up. My clients love the fact they are able to achieve this improvement and feel in control and safe when using this heavy weight.To achieve this really shows overall body strength. After all 12 kilos is more than half a full suitcase!