Slab serifs form a large and varied genre. Some such as Memphis and Rockwell have a geometric design with minimal variation in stroke width: they are sometimes described as sans-serif fonts with added serifs. Others such as those of the Clarendon genre have a structure more like most other serif fonts, though with larger and more obvious serifs. These designs may have bracketed serifs which increase width along their length before merging with the main strokes of the letters, while on geometrics the serifs have a constant width.