Disc recorders designed for amateur home use began appearing on the market around 1940, but their high prices limited sales, and then World War II brought their production to a halt. After the war, the popularity of such recorders greatly increased. It was not unusual for a carnival, circus, amusement park, or transit hub to offer disc recording in a booth for a modest fee. Countless discs were cut at parties and family gatherings, both for immediate amusement value and to preserve audio "snapshots" of these events and of the voices of relatives and friends. Schoolchildren and adults alike used them to practice speeches, amateur musical efforts were immortalized, and snippets of radio broadcasts were captured, all limited by the three- or four-minute maximum playing time of the 78 rpm large-groove format which was still standard for all home-use records. The home recorders typically had two tone arms, one for recording and the other for playback, and a red light to indicate recording was taking place. One problem with the process was the "string" of aluminum that followed the recording tone arm as the groove was cut. This "string" could interfere with the recording process and required manual intervention to remove.