500' cable and depth capability:  Price: $3,995.
For towing at even deeper depths, the Proton 4 can be purchased with a 500 foot depth rated housing and a 500 foot cable instead of a 150 foot cable.

1,000' cable and depth capability:  Price: $6,995.
For towing at very deep depths, the Proton 4 can be purchased with a 1,000 foot depth rated housing and a 1,000 foot cable instead of a 150 foot cable.

DDW-1 Deep Dive Wing :  Price: $1,295.
The deep dive wing is designed to tow equipment deeper using less cable.  A typical ratio of cable length to tow depth is 4 to 1 which means 400 feet of cable is needed to tow at a depth of 100 feet.  By using the wing the ratio is reduced to 2 to 1 which means the equipment can be towed 100 feet deep using only 200 feet of cable.

Built in printer (prints gammas and Loran/GPS cords):  Price: $995. 

RS232 Output Interface:  Price: $795.
This option converts the Proton 4 readout information into a format (ASCII) that can be read by a computer (interface cable provided). Included with this option is an input jack on the Proton 4 control box to connect a GPS system. The  Proton 4 readout and the boat's GPS position can then be sent to the computer. See Data collection software below.

Data collection and storage software (for windows 3.1 or XP):  Price: $995.
Optional Tracker software shows the path of the boat as it moves over the search area along with a cascading waterfall of the mag readouts and the GPS position associated with each readout.  When a target is detected, the readouts and coordinates change color so the operator can quickly see when and where a target is detected.  At the bottom left of the screen is a graphical representation of the last 5 minutes of mag readouts.  When a target is detected a spike or deep V is drawn on the graph.   In addition to the mag and GPS data, other information displayed are the boat's speed, compass heading, and the sensitivity setting selected by the operator.

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UA-2 Altimeter :  Price: $1,895.
The altimeter shows the distance between the Proton 4 towfish and the ocean bottom.  The UA-2 transducer mounts on the underside of the towfish.  The topside control/readout unit is in the boat.  The distance can be shown in either feet or meters, and is displayed on a two digit LCD. An adjustable audio alarm lets the user set the distance which will trigger the alarm.