There is a knack to fitted them to make them believable though. Chose the colour you want then match it with a tin of paint from your local car store. Wire brush the caliper and wipe with thinners. Trial fit the caliper and chop off bits till it fits properly (and clears the wheel when fitted).
Then paint the caliper with several coats till you are happy, no need to mask the disc as the paint will come off the first time you use the brakes.
Use clear silicone sealer in blobs on the back then secure in place with masking tape. Make sure the bleed nipple faces up!
The final effect is worth the extra effort