What is a tag? Some of the most common styles of graffiti have their own names. A "tag" is the most basic writing of an artist's name, it is simply a hand style. A graffiti writer's tag is his or her personalized signature. Tagging is often the example given when opponents of graffiti refer to any acts of handstyle graffiti writing (it is by far the most common form of graffiti). Tags can contain subtle and sometimes cryptic messages, and might incorporate the artist's crew initials or other letters. One form of tagging known as "pissing" is the act of taking a refillable fire extinguisher and replacing the contents inside with paint, allowing for tags as high as approximately 20 feet (6.1 m). Aiming and keeping a handstyle steady in this form of tagging is very difficult, usually coming out wavy and sloppy. Another form is the "throw-up", also known as a "bombing" which is normally painted very quickly with two or three colors, sacrificing aesthetics for speed. Throw-ups can also be outlined on a surface with one color. A "piece" is a more elaborate representation of the artist's name, incorporating more stylized letters, usually incorporating a much larger range of colors. This of course, is more time consuming and increases the likelihood of the artist getting caught. A "blockbuster" or "roller" is a large piece, almost always done in a block-shaped style, done simply to cover a large area solidly with two contrasting colours, sometimes with the whole purpose of blocking other writers from painting on the same wall. These are usually accomplished with extended paint rollers and gallons of cheap exterior paint. A more complex style is "wildstyle", a form of graffiti usually involving interlocking letters and connecting points. These pieces are often harder to read by non-graffiti artists as the letters merge into one another in an often-undecipherable manner. Some artists also use stickers as a quick way to do catch ups. While certain critics from within graffiti culture consider this lazy, stickers can be quite detailed in their own right and often, are used in conjunction with other materials. Sticker tags are commonly executed on blank postage stickers, as these can easily be acquired with no cost on the writers part. Many graffiti artists believe that doing complex pieces involves too great an investment of time to justify the practice. Doing a piece can take (depending on experience and size) 30 minutes to months on end, as was the case for Saber MSK while working on the worlds largest graffiti piece on the LA river. Another graffiti artist can go over a piece in a matter of minutes with a simple throw up. This was exemplified by the writer "CAP" in the documentary Style Wars, who, other writers complain, ruins pieces with his quick throw ups. This became known as "capping" and often is done when there is a "beef" - conflict between writers.