Conical 4" (10.2cm) neck for use with 6475, 6476, 6477, 6479, 6480, 6481, 6491, 6492, 6497, 6498 and 9656 ACE Reaction Flasks. Supplied with three outer joints in line, plus a 10/30 joint for a ground joint thermometer. Use 6496 Clamp for securing to f