Hampshire Constabulary said the incident took place at Travis Perkins on Parham Drive, between 11.10am and 11.20am on August 29.
A Honeywell Programmer, valued at £98, was reported to have been stolen.
The force has now released CCTV images of two people they believe can assist in their investigation.
The first man is described as of large build and wearing black trousers, black hat and a grey jumper.
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The second man is described as of slim build, ginger hair and wearing black clothing.
A police spokesperson said: “Do you recognise these men?
“We believe the men in these images can help us with our investigation and would urge them, or anyone who knows their identity, to get in touch with us.
“Also, if you witnessed anything of the incident, saw anything else suspicious in the area at the time, or have any CCTV, mobile phone, dash cam or doorbell camera footage which could aid our investigation, please contact us.”
You can do this by calling 101, or by reporting online via the Hampshire & Isle of Wight Constabulary website, quoting incident number 44240370774.
