HALO Pro® SRI – In-line PTT Interface (Intrinsically Safe)

  • Intrinsically Safe
  • Water-Resistant
  • Easy to locate and use Push-To-Talk (PTT)
  • Raised PTT button
  • 360° rotating Clothing Clip
  • Full Duplex Communication capable (depending on host radio)
  • Compatible with a wide variety of headsets
  • Jam-proof Switches
  • No Power required
  • Curly Cord, SEDFLEX, Extended Length: 1.2m (4”)
  • 2 Year Limited Warranty

Halo Pro® Series offers more Intrinsically Safe Radio accessories than any other Radio Communication System in the market.  It allows Users to connect Headsets and Radios using a UM (VOX/PTT) or SRI (PTT only) interface or just connect the headsets with a host radio.  Hazmat, high noise, wet and dirty environments, can finally be handled with confidence using the HALO Pro® Intrinsically Safe series.  The belt or carabiner mount Interfaces are energy efficient and can last several days without recharging.  With a choice of application-specific Headsets and the clearest audio in the business, HALO Pro® Series makes it easy to add versatility to your existing Radio Communication System without compromising intrinsic safety.

The Halo Pro® SRI Interface is an in-line interface for use between a hand-held portable Radio and a Headset.  The Halo Pro® SRI unit requires no power and provides the User with a remote PTT button near his/her chest, allowing the User to operate a portable Radio in difficult-to-reach conditions.  A large 4cm (1.5”), easy-to-locate, jam-proof PTT button makes HALO® SRI a perfect choice for use with bulky gloves and in tight spaces.  

What is Intrinsically Safe?

Intrinsically Safe means that the system is incapable of causing an explosion or being a source of ignition in the presence of potentially explosive or combustible materials and gases.  In other words, the equipment and wiring are incapable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture in its most easily ignited concentration.  OSHA and MSHA have many reports of fires caused by non-intrinsically safe systems.  Preventing fire and explosions is a top priority for all industries around the world. 

Other Similar Products 

HALO Pro® SRI – Intrinsically Safe In-line PTT Interface

HALO Pro® UM – Intrinsically Safe Belt-mounted VOX/PTT Interface

HALO® Headsets – Intrinsically Safe Headset Series

Ulti-Mate® – Non-Intrinsically Safe Belt-mounted VOX/PTT Interface

Additional information

DSP (Digital Signal Processor)


System Type

Wired to mate with Radio

Radio Compatible


AM/FM Radio


Intercom Feature


Intrinsically Safe


Redundant Power Supply


Hearing Aid Compatibility


Personal Volume Control

No, only via Radio



RFI Immune (Radio Frequency Interference)


Transmit Power


Communication Range


Power Supply Type

No Power needed

Battery Life


Power Supply Range


Low battery Indicator


Operating Temperature

-20°C to 60°C

Product Dimensions

2.8" x 2.5" x 1.6"

Limited Warranty

2 Years




  • Confined Space
  • Fire/Rescue
  • High Angle Rescue
  • Military/Ballistic Helmet or with Hardhats
  • Storage Tank Cars or Ship’s Holds
  • Utilities
  • Manufacturing
  • Silos and Grain Elevators
  • Sewer Maintenance


  • Remote Speaker and attachment assembly for Headset
  • Throat Microphone, In-Mask Microphone or Helmet Mounted Microphone 
  • Radio Adapter Cord
  • Universal Charger


  • Intrinsically Safe and Non-Incendive Equipment for Use in Hazardous Locations
  • Approved by CSA and UL as per CSA C22.2 No. 157-92 (R1999) and UL #913 7th Edition to meet all parts thereof and describes as:
      • Class I Div. I Groups A, B, C, D
      • Class II Div. I Groups E, F, G
      • Class III Div. I
      • Gaseous Mines
      • ITS File No. 3099473CRT-002

Compatible Headsets

Intrinsically Safe Headsets – Halo®


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