Are replacement black plastic port cable glands for the 550 available to order? I’ve been searching and can’t seem to come up with any p/n’s. Our tower guys have lost a bunch of them. 
There are no p/n from cambium that I know of (please correct me with a P/N if now available!)
With the ptp600 radios we found the glands were a standard gland and easily obtainable through other channels.
The glands I currently have are PG13.5 and PG23, I am out of the PG16 at the moment.