TFV4 Micro and Plus Extension Tubes:

The short extension tube is compatible with both the TFV4 Micro 3.5ml glass and the TFV4 Micro Plus 5.5ml glass. On the other hand, the long extension tube is designed specifically for the TFV4 Micro 5ml glass. These extension tubes are essential for those who want to increase the capacity of their TFV4 Micro and Plus tanks.