You are buying an Oval 3 Pump Overlay that fits an Oval Balboa E8 with a Cat 5 Type plug end that uses only 6 or 7 of the buttons.  Note: These topsides do fail and usually the buttons to the left of the screen are what fails on either style of topside..

Balboa Water Group VL702S Spaside Control

This overlay is for a topside control is made for use on Balboa VS510SZ and VS520SZ systems. It has a 7ft cord with an 8 wire phone jack style plug and comes with an overlay. 7 Button layout is:

Top Row- Light, Space , Mode, LCD display, Warm.

Bottom Row- Jets 1, Jets 2, Jet 3, LCD display, Cool.
 
The below list of parts are all related to this part:

Balboa, ML702, Cat 5 Plug, (2) Pumps, Blower, Light, Mode, Temp Up & Down, Time, Hawkeye

Overlay, Balboa, ML702, (2) Pumps, Light, Mode, Aux, Temp Up & Down, Hawkeye

Overlay, Balboa, ML702, (3) Pumps, Light, Mode, Temp Up & Down

Overlay, Balboa, ML702, (2) Pumps, Blower, Light, Mode, Temp Up & Down

This overlay fits a topside with the following specs..
Manufacturer    Balboa Water Group
Topside Complete    Complete Topside
Model    VL702S
Buttons    7
Topside Shape    Oval
Panel Size    10-5/16" x 4-5/8"

Hole Size       6 3/8" x 2 1/4"