The Kendall 6325 Response Compression System is designed to apply sequential compression to the lower limbs to help prevent deep vein thrombosis in patients at risk. The model 6325R Controller has been upgraded from an SCD Sequel Compression System Model 6325 Controller. The System consists of the Model 6325R Controller, the Tubing Set (provided with the Controller), and the use of single-patient use SCD Sleeves (purchased separately from this Controller). The Sleeves compress the limbs to enhance venous blood movement. After the compression, the Controller measures the time it takes for the legs to refill with blood and waits that period of time before the next compression in initiated.