Some enzymes make strand incisions immediately opposite one another.These ends are called as "blunt" (meaning "not sharp") or "flush" (meaning "level or even").

For example, the enzyme Sma 1 cuts in the middle of the six nucleotide recognition sequence:

5'-CCCGGG-3' Sma I 5'-CCC -3' + 5'- GGG-3'
3'-GGGCCC-5' ----> 3'-GGG -5' 3'- CCC-5'