This gas spring consists of two distinct chambers, a gas chamber and an oil chamber. While extending, the piston moves exclusively inside the oil chamber, thus avoiding any damping during extension. It is used where rigidity is required during extension & a minimum spring effect is desirable during compression, e.g. fowler beds in hospitals, dental chairs, etc.
As opposed to RABE, the piston rod in this gas spring moves through both the chambers of oil and gas. But during compression, the piston rod can move through and only against oil. This provides rigidity during gas spring compression.