This construction is ideal when, for example, the amount of space for the pool length is limited. The underwater grating closes off the cover pit apart from a small slit around 8 cm wide. The covers on the underwater grating are not screwed on, and can be removed for cleaning. The roller system should, if possible, be positioned on the skimmer side so that, in the case of an outdoor pool, the coarse contamination is transported directly in front of the skimmer.
| Construction: | Roller system below the bottom of the pool with a fixed pit cover (underwater grating) |
| Installation: | Only for new pools |
| Maximum size: | 25 m x 50 m (larger sizes depending on pool shape) |
| Drive unit in separate motor pit: | Drive unit mounted on the shaft, or chain drive |
| Cover slats: | Standard slats 60 mm wide and 14 mm thick |
| Guidelines: | Installation approved only for private pools |