Checkbox array
php
['var' => 'col', 'label' => 'Sizes', 'type' => self::TYPE_CHECKBOX_ARRAY, 'options' => [
'items' => [
['value' => 1, 'label' => '30%'],
['value' => 2, 'label' => '40%'],
['value' => 3, 'label' => '50%'],
['value' => 4, 'label' => '60%'],
]
]],