This is Seacam's original fisheye macro port. It was designed for use with the Sigma 15mm f2.8 fisheye. But to fit the lens into the port you need to remove part of the fisheye's lens shade. The port has scuffs on the delrin body but the glass is pristine. I think the new cost was about $750. I'll sell this one for $450. If you do not have a Sigma fisheye with a "shaved" lens shade I am selling one of those, too. Offers or questions please write to me at fbavendam@hotmail.com. Thank you
