by Magnum , and is issued to more combat focused units in the Singapore Army, such as the infantry, armoured infantry, guards, and commandos. It has a hybrid leather-fabric upper like the ACB, but with a lighter weight, fully stitched cupsoles, and an outsole design that is more suited for both urban and jungle environments. Both the ACB and the ECB have been in use since December 2016. Past versions of boots issued within the Singapore Armed Forces include a full leather upper boot with a reinforced toecap (in service until 1993), an improved version that removed the reinforced toecap, reducing weight, and had improved insoles that provided more support and offered better hygiene (in service 1993-2002), the 'Gore-Tex' boots, a revised design with parts of the upper made of Gore-Tex, making it waterproof (in service 2002-2012), and the 'Frontier' boots (named after the manufacturer), of which the Gore-Tex material was replaced with a porous nylon fabric for quick drying, and featured water drainage holes, thus no longer making the boots waterproof (in service 2012-2016). The Frontier boots also had a redesigned sole that were supposed to give improved agility and comfort. The Frontier boots had received criticism from some Singapore Army reserve conscripts who were previously issued the Gore-Tex boots. Unlike its predecessor, the Gore-Tex boots, which were padded and waterproof, the Frontier boots did not feature the padding, and instead had an added ankle support strip, which some servicemen claimed made the boot more uncomfortable. The revised design also lost its waterproof properties, which also drew criticism. However, it allowed water to drain out of the boot after a river-crossing. Also, the boot became more ventilated and thus cooler with the revised design. Durability was also an issue in both the 2nd Generation Gore-Tex and also some batches of the Frontiers. At times, the sole of the boot will come apart since it is only glued to the shell of the boot and not stitched. Some servicemen would also find their Frontier boots' stitching coming apart after some weeks of usage, or even the soles disintegrating and cracking after prolonged use or storage. The succeeding ACB addressed the durability issue with directly molded soles, and is also purportedly more comfortable. Non-aircrew servicemen of the Republic of Singapore Air Force are issued the RSAF Combat Safety Boots, manufactured by Frontier, for use in airbases. The RSAF boots feature padded