Camera Iris Mechanism.Built to aniamte open and closed. Great detail level suitable for close up work. Makes great Sci-Fi doorways etc.Built in 3DS Max 7.0, and exported as a 3DS file. Opened, checked, and rendered in Maya 7.0 for export integrity. NOTE 3DS is an export format and some slight smoothing group adjustments and pivot point adjustment will be needed as there are limits to the 3DS export format.