The air gap between the two walls creates a layer of isolation for the roots of the plant. And protects them from frost and heat. Double wall pots are protected for heavy sun burn of the outside layer and prevent the roots from burning.

Potted plants need to be showcased in flowerpots equipped with a good drainage system in the event of over watering, whether from natural rainfall or over watering by an eager gardener.
Unless excess water can filter through the soil and drain away from the roots of your potted plants, the roots may develop root rot if they are exposed to standing water for an extended period of time. Root rot will eventually cause your potted plant to whither and die since it will rob the plant of the ability to draw moisture and nutrients from the soil.

Udaes di di re eumque es sum es velitas etur? Quiaes illuptam reriore icilis nimus, ullam harcia sitatia pa que comnimagnam, nonet pro el imus

Otium Olla135, Amphora 75, Murus (27&90) and Linea (40&100) are provided with an extra weight system. The system is simply a closable opening. Through the free space between the two walls there is enough space to pour grind or gravel in the pot.
If enough weight is inserted, the pot will have extra stability and will not fall over in strong