Rashr is a popular root application known for flashing kernel and recovery image files on android devices.
Besides flashing recovery and kernel image files, Rashr can also be used to backup stock recovery and kernel files or whichever one that's currently flashed on the supported android device.
The recent 2.3 update of the Rashr application now supports more phones and more image files are loaded and can be downloaded easily on the phone from within Rashr applications.
If you actually wish to flash custom recovery on your android device or wish to backup your android device recovery partitions and kernel, you should consider using Rashr.
Source: Aryk Enterprise Blog