I had to cut both the front and rear lines, an easy job with a box knife on a hard surface. Once the lines are cut, the system has to be bled, but these are about as easy to bleed as they come. The two-finger lever is very comfortable. Since these are powerful brakes, two fingers are more than necessary for most occasions. The reservoir is located at the top of the lever, and the lever is only adjustable for reach.
Hydraulic brakes come in two flavors, open and closed.
The former has a reservoir that allows heated brake fluid to expand. This same reservoir allows fluid to flow into the hoses as the pads wear, eliminating the need for external wear adjustments. A closed system may or may not have a reservoir. If it does, it is for manual adjustment for wear or for fluid expansion. As stated, the O2's are an open system.