AquaComputer have two different D5 tops.  Both of these can be used as standalone tops or mated directly to a compatible “Aqualis” Reservoir.  The two versions are differentiated by the presence of a “fill level sensor”.  This fill level sensor measures the water pressure at the bottom of a compatible Aqualis reservoir.  The more water is in the reservoir the higher the pressure.  The fill level sensor itself uses the same design as the MPS400 flow sensor that was reviewed here.  The sensor still measures a differential pressure and so one end of the sensor is connected to the ambient air pressure.  The fill level sensor functionality will be covered in a separate review.  The top comes in the usual pretty AquaComputer packaging:

Accessories including a mounting bracket, stop fittings and a cable to hook up to the fill level sensor.

The top has two inputs and two outputs, only the front ports are labelled, but the top ports are simply in line with the front ports:

The stainless steel section on the right side of the top is the differential pressure sensor implanted into the side of the top.  The third smaller hole on the top side is the sense point for the pressure sensor that acts as a fill level measuring sensor.

The volute is a fairly complex design and it can be seen that the outlet port is not directly inline with the output of the pump itself. The front port instead is doglegged and two 90 degree bends seem somewhat unnecessary:

This does not appear to be due to a lack of space because the design is already much bulkier than the competition.

There are four mounting points for the bracket which is an upgrade from the usual two. The bends in the stainless steel mounting bracket should also help to isolate vibration a little.