A base for supporting posts of fencing, which base includes a block of plastics provided with apertures for receiving the ends of fencing posts. Each end of the block is provided with a gripping portion which projects longitudinally away from the main body of the block. A first interlocking means is associated with one of the gripping portions and interlocks with a corresponding second interlocking means of a cover which is fitted to the block over the gripping portion. The cover is of enhanced visibility compared to the main body of the block which is of a dull color.