"What's the basin for?"
The basin holds the pump and provides a place for the water to fill before the pump moves it out. The lid on the basin also keeps the water from overflowing out of the basin; instead, the water will temporarily back up from the source until the pump catches up. This helps prevent water damage.

"What does a check valve do?"
The check valve keeps the water from coming back into the pump after it's been pumped out.

"What's the difference between an automatic and non-automatic pump?"
An automatic pump has a built in float switch that will turn on the pump automatically at a fixed water level. After the water is pumped out to certain water level (also a preset level), the pump will turn itself off. A non-automatic pump has to be manually turned on and off, or with a separate control like a piggyback float switch.

"What does a 'trap' do? Do I need it for my pump to work?"
A trap just keeps the smell of the drain from coming into your a room through the fixture drain.

"What does it mean by 'slip fit' for a top and side intake?"
The pipe just slips in rather than being glued together. This means you don't have to break the pipe to remove/replace the basin.

"What is the 10' stack test?"
This means that the basin can withstand water pressure from a 10' vertical pipe without leaking.

"What is a 'slip x slip union'?"
The check valve is mounted with rubber couplings for easier installation and servicing.

"If I buy a drain series with a M50 series pump, can I buy a different M50 series pump to replace it?"
Yes, the M50 series pumps should be compatible with the basin and lid, internal discharge pipe to lid, and check valve that came with the original pump.

"What is a vortex impeller and what does it do?"
A vortex impeller handles debris better than other impellers. It's used to help prevent clogging in your pump. Below is an example of a vortex impeller.