WC : S-trap

If you look at the cross section of the throne, the passage in black is in a S shape.
the distance from the wall to the center of the hole is 150mm = 6"



6" is the distance from the wall to the center of the hole. the hole size is quite standard.
there is also a 9" model.

if you original setup is 6" or 9", you will not need a offset, water will flow very smoothly.
an offset is a plcae of plastic that allows us to have a -+ of up to 2 inches
eg, sometimes u overlay wall tiles and it adds 1 inch thickness to the wall, u'll need a 1" offset to adjust the fitting to 5" from the wall.

There is also P trap for waste pipes that are running into the wall instead of floor.

The reason I stick to Rigel is their product have gone thru PSB testing and is PLS.
If you noticed, some authorities will still insist only PLS suppliers to participate in the tender.

Why Rigel is cheap.? bcoz they are the manufacturer and they sell direct to customers without going thru dealers.

Have fun searching for your WC.