INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'django.contrib.admin',

    #.....................#

    'multiselectfield',
)

from multiselectfield import MultiSelectField

...

class MyModel(models.Model):

    .....

    my_field = MultiSelectField(verbose_name=_('xxx'), choices=MY_CHOICES)

git clone https://github.com/goinnn/django-multiselectfield