This model sinks without weights. 
 
This adult model is made of durable vinyl plastic with rust-resistant stainless steel skeleton, articulated joints, and optional CPR capabilities
When filled with water, CPR manikin will sink, a flotation device is needed
Includes 5 mouth/nosepieces, 5 airway systems, and shorts
Size: 49 in. x 16 in. x 9 in ( 125 x 41 x 23 cm )
 
Sh. Weight: 24 lbs. (10.89kg)