Within fair faced blockwork, an appropriate choice of size is important for both coordination and visual scale. While blocks may be cut with a masonry cutter, the addition of small pieces of block, or the widening of perpends over the 10 mm standard, is unacceptable. The insertion of a thin jumper course at floor or lintel height may be a useful feature in adjusting the coursing. Curved blockwork may be constructed from standard blocks, the permissible curvature being dependent on the block size. The oversail between alternate courses should not normally exceed 4 mm in fairfaced work. If the internal radius is exposed, the perpends can be maintained at 10 mm with uncut blocks, but if the external radius is exposed, the blocks will require cutting on a splay. For tighter curves specials will be required.