positioned such that the bag will be stretched and expand as the device 10 is operated fig2 a prop guard 24 is fixed in front of the prop inside the casing unit 16 between the prop blades 22 and the bag 26 this guard 24 prevents the bag 26 inside the casing 16 from contacting the blades of the prop 22 fig2 4 a flexible bag like structure 26 is attached to the closed or second end of the casing unit 16 it allows water to move through it but traps any solid materials within the bag on the side of the casing unit 16 there is a small side flap 17 which acts like a single directional check valve and allows water out when the device is idle a screen 15 may also cover this flap to add another measure of safety to prevent any debris from entering the casing and damaging the prop 22 fig1 this small side flap 17 is used to help empty water from the casing 16 as the vacuum 10 is removed from the pool or spa when the unit is on the suction which is created by the device 10 will force this flap 17 closed on the second end of the casing unit 16 the vacuum attachment 35 located at the suction end 12 to collect the debris is attached to the.