Tactical communications hardware encompasses the headsets, push-to-talk devices, speaker microphones, cables, and mounting accessories that connect a user’s radio to their ears and voice. T.REX ARMS curates a focused selection of these components—primarily built around OTTO and Kenwood-compatible hardware—to simplify what can otherwise be an overwhelming array of options.
Radio Connector Standards
The most common connector for civilian handheld radios is the Kenwood 2-pin plug. The majority of comms accessories T.REX offers use this standard. For radios that do not natively use Kenwood 2-pin, adapters are generally available to bridge the gap. Standardizing on a single connector type simplifies cable management and allows accessories to be mixed and matched across different radio platforms.
Push-to-Talk (PTT) Devices
Nexus U94 PTT
The Nexus U94 is the most widely used push-to-talk form factor across both civilian and military applications. Its appeal comes from a combination of small size, simplicity, durability, and low cost. A large PTT is considered a disadvantage—it adds bulk and complicates cable management on an already cable-intensive setup.
Mounting to a plate carrier: The preferred method is to remove the belt clip from the back of the U94 (four flathead screws) and secure the PTT to vertical MOLLE webbing using a sling keeper or similar retention device. On carriers like the AC1 that have vertical MOLLE spacing on the front, the PTT sits slim and low-profile. For slick-front carriers (such as the MBE or AC0), the PTT can be secured lengthwise to placard tabs using the same sling-keeper technique, ideally with the cummerbund running over the top to prevent cable stress.
Speaker Microphones (Cop Mics)
The OTTO speaker microphone provides a more flexible and cost-effective communications solution than a full headset-and-boom-mic setup. Its primary advantage is that it does not require a communications-capable headset to function—the user simply keys the mic, speaks toward it, and listens through either the built-in speaker or an attached earpiece or headset.
Key features of the OTTO cop mic:
- Volume control: Two-position switch (high/low) on one side, which also governs volume sent to any connected headset.
- PTT button: Located on the opposite side from volume control.
- 3.5mm auxiliary jack: On the bottom of the unit, accepting a standard 3.5mm cable to route received audio into headphones or an earpiece.
- Durability: Waterproof and dust-rated, notably smaller than military Harris or Thales speaker mics while maintaining environmental protection that cheaper, smaller alternatives lack.
A common operational configuration is running two radios with a cop mic on each side of the chest. This setup allows the user to operate with or without a helmet and headset, adapting to the situation.
Earpieces and Audio Routing Cables
Covert Earpiece
A single in-ear earpiece that plugs into the 3.5mm jack on a cop mic, allowing the user to monitor radio traffic discreetly without headphones and without broadcasting received audio to bystanders. A plastic shirt clip manages cable tension to prevent the earpiece from being pulled out. The earpiece does not create an acoustic seal, so ambient awareness is maintained.
Range SA Down Lead Cable
A proprietary auxiliary cable designed to connect OTTO headphones (both Range SA and TAC variants) to a cop mic’s 3.5mm jack. This routes received radio traffic directly into the headphones. The cable plugs into the two-port connector on the back of OTTO headphones. When used with the TAC (communications-capable) headphones, the boom mic can be unplugged and replaced with this cable to run the headset in a slick, receive-only configuration identical to the Range SA setup.
Additional Down Lead Cable
OTTO NoizeBarrier headsets ship with one download lead cable. A second cable is required for dual-comm setups (monitoring two radio nets simultaneously). It plugs into the opposite side of the headset in the same manner as the included cable.
Helmet Mounting
The OTTO NoizeBarrier Helmet Mount Kit allows OTTO headphones to be mounted on Ops-Core style helmet rails. Key characteristics:
- Locking mechanism: Clips lock with an audible click and require a deliberate pinch to release, unlike Peltor-style mounts where outward force alone can dislodge them.
- Rotation: The mount arms spin freely, allowing the ear cups to be oriented anywhere along the rail. This lets users mount traditionally (above the ear) or toward the rear of the helmet to keep forward rail space open for lights and other accessories.
- Increased NRR: The mount kit creates significant clamping force, which can actually increase effective noise reduction by compressing the ear cups more tightly against the head.
- Battery storage: A small compartment in the mount arm holds a spare AAA battery, though it becomes difficult to access once mounted.
- Rail retention: Zip ties through the rail holes are recommended as stops to prevent the mounts from accidentally sliding off, as rail tolerances can vary between helmets.
Storage note: When storing a helmet with mounted headphones, the ear cups should be clipped inward inside the helmet shell. Rotating the cups flat against the helmet exterior and clipping them down risks bending the rail and damaging the gel or foam cups due to the mount’s strong clamping force.
In-Ear Electronic Hearing Protection
The OTTO NoizeBarrier Micro electronic earplugs serve as a lightweight alternative to over-ear headsets for specific use cases: outdoor pistol shooting, bolt-action and suppressed rifle use, and competition events like the Tactical Games where over-ear protection creates heat and bulk issues. They are explicitly not recommended for indoor shooting or sustained rifle fire, as in-ear protection cannot block noise entering through surrounding soft tissue and bone the way over-ear cups can. High NRR numbers on in-ear devices should be taken with caution, as lab-measured seal performance does not account for these alternative noise pathways.
The Micros feature a rechargeable carrying case with an LED display showing individual earpiece and case charge levels, two selectable ambient volume modes (high and low), and replaceable wax filters. Foam tips are recommended over flange tips for better protection, though they wear out over time and require proper insertion technique for an effective seal.