Thetis Ballasted Filter Mattresses are prefabricated concrete elements typically used for the stabilization of mobile underwater beds or for shoreline protection in erosion-prone areas. They are also widely used in port environments to protect docks and quays from the erosive action caused by boat propellers.

These mattresses consist of a geotextile fabric ballasted with concrete blocks, which are secured to the fabric through the insertion of special polypropylene nails.

The handling and installation are carried out using a specially designed frame equipped with automatic release clamps, allowing the mattress to be lifted from both free ends.

The production of Ballasted Filter Mattresses is typically done with a block-making machine (forming machine), which enables the production of mattresses with thicknesses ranging from 10 cm to 30 cm. For greater thicknesses, metal molds specially designed and constructed are required.