Products themselves are solid and well made. The posted required hole diameter on the product page is mistaken when it says you need a 1.125" hole for the 1/2" Diameter Bulkhead. I bought (3) 1/2" and they were all Thread OD of 1.14". Now I understand that when you cut a hole you often end up with slightly oversized or undersized holes depending upon quality of the bit. On my Acrylic Aquarium they were dead on 1.125". That being said I simply broke out some 100 grit sandpaper wrapped around a jumbo marker and opened up the hole. Should you be dealing with a Glass hole you may not be so lucky. So not sure if the MFG over sized the OD of the threads or the hole size was misprinted. I think the threads are correct and the chart is off. The 1" Bulkhead has a thread OD of 1.680" so the chart listed hole req of 1.75" is OK. I didn't buy any other sizes but keep it in mind. If your stuck with glass you may be able to sand the threads OD to reach a tighter hole, insert bulkhead, wrap exposed threads in pipe tape and then tighten the nut.

Not using for a aquarium so thread length was short but the table I'm using is hollowed core. Sorry not much to say about the bulkhead it's a good solid product

This bulkhead was exactly what I needed for my aquarium. Its threads allow its use with PVC tubing available at a hardware store. I used some Teflon tape, andI had no problems with leaks. It did not fit perfectly into the 1-1/8" hole I drilled at first, but after I enlarged the hole slightly by pushing the hole saw against the sides, it fit well.