what is the difference between top, rear, bottom mount gauge

[rastoma]

I think I need to replace the pressure gauge on my sand filter. Looking at various online retailers it shows the same picture for every description of gauge whether it's bottom mount, rear mount or 'STANDARD' mount.... like I know what standard is.

Does it matter as long as it screws in and I can see the gauge?

 

[rastoma]

nvm... finally found some pics on Ebay that show me the difference

 

[JasonLion]

The only difference it really makes is how easy it is to read the legend on the gauge.