According to Official Guinness Records,
The largest clothes peg measured 3.5 m (11 ft 5 in) long, 65 cm (2 ft 1 in) high and 44 cm (1 ft 5 in) deep. It was created by Karl Josef Biller (Germany) and was presented and measured in Regensburg, Germany, on 9 September 2012.
The peg was made out of wood. The peg was opened and closed in front of the witnesses.
For a complete list of 2012 records, please visit 2012 Guinness Records in Germany.