Why do need these Solid State Relays or switches or any related items from this site? It is easy to answer really: because they all work. Yes, they are fully functional items and thus will never let you satisfaction and expectation go low.
If you have been in that tricky situation where you flick something and nothing turns out to be turning on, you will certain understand the gravity of the situation here. Those switches and relays, small as they are indeed, are ones of the most important devices that make any operation or process, as far as it involves electrical current jumping or cutting, successful. And the simplest example of such operation is your switching on or off of your own bed room.
Of course, the larger the room or situation, the bigger the current you need to by-pass. Imagine the scale of the whole electrical current supplies that you need to regulate in your own manufacturing or industry level. You cannot rely on such a critical distribution of energy into lower quality switches or relay monitors. Else, you will have to face a constant threat of jeopardizing the whole operation by high probability of having ll of those electrical shortcuts in any of your terminals.