
Preferred Partner for SF customers
SIEL: Italian manufacturer of combat diving equipment and unmanned marine systems.
SIEL S.r.l. is an Italian defence manufacturer, founded in Turin in 1967, that produces oxygen rebreathers, tactical diving equipment and underwater navigation and communication systems for combat divers, as well as autopilot, telemetry and remote-control systems for unmanned surface vessels. SIEL states that its main users are navy, army, police and special forces units. MSS Defence is SIEL's Preferred Partner for SF (special forces) customers and handles advice, quotations and delivery.

Key Facts.
- Founded: 1967 in Turin, Italy
- Plants: Moncalieri (Turin) and Santo Stefano di Magra (La Spezia), Italy
- Quality: ISO 9001 certified quality system
- Środowisko: environmental management system to UNI EN ISO 14001
- NATO CAGE code: A5011
- Users: military forces in more than 50 countries
Oxygen and mixed-gas rebreathers.
The SIEL CAIMANO MK4 CDV PRO is an oxygen closed-circuit rebreather for combat divers with a nominal endurance of 240 minutes and a weight of 10 kg ready to dive, according to SIEL. The SIEL SEAL MK1 PRO is a smaller oxygen closed-circuit rebreather with a nominal endurance of 90 minutes and a weight of 6 kg ready to dive; SIEL positions it for amphibious operations, boarding and short diving missions.
The SIEL CAIMANO MK4 CSC PRO uses the same front unit as the CAIMANO MK4 CDV PRO and can switch from oxygen closed-circuit to mixed-gas semi-closed operation, with the mixed-gas unit worn on the back, on the leg or as a twin unit. The SIEL Multiscan gas analyser measures oxygen partial pressure (PPO2) and oxygen percentage (%O2) through the rebreather counterlung, and also records depth, maximum depth, EAD depth and dive time.


Tactical diving equipment.
SIEL also supplies the equipment around the rebreather: the TACTICAL LIGHT and OL-TAC RIPSTOP NYLON II dry suits, thermal undergarments, Monoprene fins, Sea Eagle amphibian boots, Tactical Kevlar neoprene gloves made of 5 mm neoprene, waterproof bags including a shoot-through rifle bag, dive lights and wing buoyancy compensators.
The SIEL Triton K2 air regulator has a 232 bar DIN connection, two high-pressure and four low-pressure ports, and a 760 mm low-pressure hose. The SIEL Triton console combines a 400 bar pressure gauge with a 70 m depth gauge, and SIEL depth gauges are available with 0–16 m, 0–25 m and 0–80 m scales.
Gas booster systems.
The SIEL GBS gas booster system refills one to six cylinders at the same time and is driven by compressed air, so it needs no electric power. The SIEL GBS-M1/232 is a single-cylinder version with a micro-booster in a carrying case. SIEL also offers an anti-deflagration container for refilling oxygen cylinders.
Equipping a combat diver team?
MSS Defence prepares quotations for complete SIEL rebreather, diving and navigation sets.

Underwater navigation.
The SIEL navigation range consists of four products. The NAVSUB diver navigation board carries a gimbal-mounted compass. The PRIMO Nav dashboard combines a bottom timer, compass and GPS navigation in one unit and has a Bluetooth interface. The MANTA digital navigation board measures distance and speed through the water with a built-in propeller. The NEXA deployable digital buoy links a dive team using PRIMO Nav units to the surface and receives GNSS position data.
Underwater communication.
SIEL makes diver communication systems for diver-to-diver and diver-to-surface voice. The SEACOM S3 surface unit combines a VHF radio with ultrasonic transceivers. The SEALAND 20 diver radio unit combines ultrasonic and radio links, and the SEACOM U5000 is an ultrasonic diver unit. The AQUAPHONE is a wired intercom with two headphones and a laryngophone, and the FALCO marine surface locator tracks a person or object on the sea surface.
Unmanned marine platforms.
In the maritime domain, SIEL designs autopilot, telemetry and remote-control systems for unmanned surface vessels (USVs), as well as mine countermeasures (MCM) and anti-submarine warfare (ASW) systems.
Specifications and quotations
SIEL publishes only limited technical data on its equipment. MSS Defence shares full specifications and datasheets on request with qualifying government, defence and law enforcement customers, and prepares quotations for complete diving and navigation sets.
Często zadawane pytania.
- What does SIEL make?SIEL, an Italian defence manufacturer founded in Turin in 1967, makes oxygen and mixed-gas rebreathers, tactical diving equipment, gas booster systems and underwater navigation and communication systems for combat divers, plus autopilot, telemetry and remote-control systems for unmanned surface vessels.
- What is the endurance of the SIEL CAIMANO MK4 CDV PRO rebreather?SIEL states that the CAIMANO MK4 CDV PRO oxygen closed-circuit rebreather has a nominal endurance of 240 minutes and weighs 10 kg ready to dive.
- What is the difference between the SIEL CAIMANO MK4 CDV PRO and the SIEL SEAL MK1 PRO?SIEL states that the CAIMANO MK4 CDV PRO has a nominal endurance of 240 minutes at 10 kg ready to dive, while the SEAL MK1 PRO has 90 minutes at 6 kg; SIEL positions the SEAL MK1 PRO for amphibious operations, boarding and short diving missions.
- Can the SIEL CAIMANO MK4 CSC PRO be used with mixed gas?Yes. The SIEL CAIMANO MK4 CSC PRO can switch from oxygen closed-circuit to mixed-gas semi-closed operation, with the mixed-gas unit worn on the back, on the leg or as a twin unit.
- How is the breathing gas in a SIEL rebreather checked?The SIEL Multiscan gas analyser measures oxygen partial pressure (PPO2) and oxygen percentage (%O2) through the rebreather counterlung, and also records depth, maximum depth, EAD depth and dive time.
- Which underwater navigation systems does SIEL make?SIEL makes four underwater navigation products: the NAVSUB diver navigation board, the PRIMO Nav dashboard with bottom timer, compass and GPS, the MANTA digital navigation board that measures distance and speed through the water, and the NEXA deployable digital buoy that links PRIMO Nav users to the surface.
- Is SIEL a certified defence supplier?SIEL has an ISO 9001 certified quality system, an environmental management system to UNI EN ISO 14001, and NATO CAGE code A5011.
- How can I get full specifications or a quotation for SIEL equipment?MSS Defence, SIEL's Preferred Partner for SF (special forces) customers, shares full SIEL specifications and datasheets on request with qualifying government, defence and law enforcement customers, and prepares quotations through the request button on this page.