TOSOH Bioscience
TOSOH Bioscience 07573 TSKgel Phenyl 5PW 7.5mm ID x 7.5cm 10µm Column
Rounded corners includes rivets, so it feels more solid than similar items without them.
TOSOH Bioscience 18759 TSKgel Phenyl 5PW 2.0mm ID x 7.5cm 10µm Column
The double ended setup means you can test both ends to see which suits you.