In the development of thin and medium-power steeply dipping seams systems with long cleaning faces on the dip the most labor-intensive and heavy is the fastening of bottom-hole space, which takes up to 55-60% of working time.

To reduce coal losses during hydraulic mining of thick steeply dipping seams by the sublevel hydraulic extraction system, flexible metal floors are used, separating coal from the caved rock and, along with completeness of extraction, allowing coal extraction to be carried out without support in the stope.