do DW sell hammers and screwdrivers?
C spanners generally come in two sizes small for 58mm ID springs and big for 65mm ID springs most of the JDM coilovers ive seen are the larger ones.
Make sure what ever spanners you buy have a nice 'grip' on the adjusting collar as a slip here = punching metal stuff.
Some are like 3mm pressed steel and are only good for adjusting brand new units.
also make sure you coat all of the adjuster threads in plenty of anti-seize if its for a road car and you dont plan on taking them apart often.