These are additional waste containers for the Festool CT-VA Pre Dust Separator.
These transparent containers are stackable; the lids seal in the dust and debris. Having an additional container allows you to swap a full one for an empty one and continue to work virtually uninterrupted. The full containers can then be dealt with in one go at the end of the day. Being clear gives you an instant visual check to see how full it is.
The CT-VA system is suitable for use with both L and M dust categories. Container capacity 20 litres, dimensions (L x W x H) 395 x 295 x 355mm.