When using a ventilation system in conjunction with a grow tent, negative pressure (more air going out than coming in) causes the tent cover to be sucked in towards the centre of the tent. On the average 1.2m tent up to 30cm of space can be lost. Expando stops this from happening. This added space allows plants to grow bigger whilst also allowing for more air to circulate, lower the risk of rot. Each Expando is adjustable from 1m to 1.5m which covers almost every tent range up to 6m. Now suitable for tent poles from 16mm to 30mm. Expandos can also be used to support Horizontal SCROG Nets and Clip Fans. Expando V2s come in a pack of 2.