2+1/2 turn, 2.5mm thick, 27.5mm diameter door handle springs plus circlips.  The additional photo gives detailed dimensions of the spring.  The circlips have an internal diameter of 13.8mm and are intended to fit a 15mm shaft with a 14.3mm groove machined into it.  This is the standard size used in the vast majority of door handles.  They are external circlips (so called because they fit to the outside of a shaft).  They should be removed and replaced using external circlip pliers.  The 2+1/2 turn, 2.5mm thick spring is the size found in many Carlisle Brass Door Handles, but please check the dimensions against your broken spring before ordering.  The springs are supplied with a passivated zinc coating for corrosion resistance.