Music rolls for the Welte-Mignon T98 system, made from 1924, are usually called “Welte green” rolls because the paper used was mostly a striking green. The red or burgundy roll boxes bear a label on the front with the name Welte-Mignon, the roll number, the title and the pianist. The same label is also on the music roll – since the roll runs from top to bottom, the label can be read normally when the roll is inserted. Some rolls also give the date of manufacture. Some rolls only have typewritten labels. There is a hook or a round eyelet at the start of the roll for hooking it into the take-up spool. This roll format corresponds in its dimensions to the 88-note standard format. The paper is 28.6 cm (11¼ in) wide.
Most Welte recordings were made with the Welte T100 (red) system. After the introduction of the Welte T98 (green) system, the recordings were re-encoded and cut in the new format. The result turned out very well. Nevertheless, many collectors prefer the “original”, i.e. Welte red. Since Welte T98 (green) only came onto the market at the end of the pianola era, it is much rarer today than its predecessor Welte T100 (red) – and so are its music rolls.