Guymager is an open source forensic disk imager tool (based on Qt) for media acquisition. This tool is only available only on Linux, and it comes pre-installed with Kali Linux. Guymager is created by Guy Voncken.
It was designed to support different image file formats, to be most user-friendly and to run really fast. It has a high speed multi-threaded engine using parallel compression for best performance on multi-processor and hyper-threading machines.