Opal (armoured personnel carrier)  The Opal"-I is a multi-purpose fully amphibious armoured personnel carrier developed and produced by HSW S.A.. APC is a development of MT-LB that was produced in HSW on licence. Major changes are with reworked nose section and propellers for better in water speed and manoeuvrability, new turret with 12.7 mm NSVT machine-gun instead of old with 7.62 PKT and powered-up engine. Opal"-II is a stretched variant with longer chassis with 7 road wheels on each side, like the 2S1 and MT-LBu and 300 hp (220 kW) SW680T engine. ("WPT" for "Wóz Pogotowia Technicznego" - lit "Technical Support Vehicle") - technical support vehicle with light crane, hydraulic dozerblade, welding equipment and an NBC detection system. The vehicle is a basic support vehicle of mechanized battalions equipped with BMP-1 IFV in Polish Land Forces. ("TRI" for "Transporter Rozpoznania Inżynieryjnego" - lit. "Engineering Reconnaissance Vehicle") - engineering vehicle with basic equipment. In use with Polish Land Forces. It's TRI "Hors" additionally equipped with trailer-mounted UZR-3 mine clearing system. In use with Polish Land Forces. ("ISM" for "Inżynieryjny System Minowania" – lit. "Engineer Minelaying System", "Kroton" is Polish for Croton) - "Opal"-II based engineer vehicle with mine-scattering system UMN mounted on a cargo bed. UMN consists of 4 launchers, each with 20 launch containers for anti-personnel or anti-tank mines. The ISM has a crew of 2 and a combat weight of 15.25 tonnes. It entered service with Polish Land Forces in 2004. Armoured ambulance vehicle. In service with Polish Land Forces. ("ZWD" for "Zautomatyzowany Wóz Dowodzenia" – lit. "Automatic Command Vehicle") - "Opal"-I based air defence command vehicle equipped with "Łowcza" system. The troop compartment section of vehicle is higher than in standard vehicle. Also known as LA-3. Vehicle is used by Polish Land Forces. ("LSPZRA" for "lekki samobieżny przeciwlotniczy zestaw rakietowo-artyleryjski" – lit. "light, self-propelled, anti-aircraft, combined gun and missile system"; "Sopel" is Polish for Icicle) - air defence variant armed with twin 23 mm cannon and two 9M32M "Strela-2M" surface to air missiles.