Ventilation

All the equipment needed to provide fresh air and control the growing environment's humidity and temperature.  Effectively all of the plants dry mass comes from the air and not from the nutrients/soil, so adequate ventilation is the key to large, healthy crops and reduced levels of disease.  By removing hot, humid air from the growing area, environmental conditions can be maintained at optimal levels for fast, healthy growth.
Desk and clip fans can be found in the electrical/hardware section.