American Optical AO Spencer 160mm tube length 10x and 20x dark medium phase contrast objectives with matching condenser annuli, please visit my eBay page for photos and details, thank you:
https://www.ebay.com/itm/154978042295
https://www.ebay.com/itm/154977996120
I also have an AO 160TL 20x dark medium phase objective without matching annulus for sale:
https://www.ebay.com/itm/154787604908