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Background: Limb tourniquets have been used extensively during modern Middle Eastern conflicts. Despite its undeniable successes, the combat applied tourniquet (C-A-T) has some shortfalls, principally its inability to reliably control lower limb bleeding when applied to the mid-thigh. We tested two tourniquets which may represent an improvement to the combat applied tourniquet; the tactical mechanical tourniquet and the tactical pneumatic tourniquet., Methods: We recruited 12 healthy service personnel and applied the tactical mechanical tourniquet and tactical pneumatic tourniquet to both lower limbs in a randomly generated sequence. Tourniquets were tightened until popliteal artery occlusion. This was measured via a SonoSite portable ultrasound machine by a single consultant vascular radiologist familiar with its use. A longitudinal view of the popliteal artery was obtained, and Doppler waveform monitored. The tourniquets were tightened around volunteers' mid-thigh by a second researcher accustomed with their use. Time to complete occlusion, number of windlass revolutions, and pain scores were collected by a third researcher. Non-normally distributed data are present as median (interquartile range). Ordinal nonparametric data are analysed by Mann-Whitney U testing., Results: Participants had a median age of 32.5 (28-35). Both tourniquets demonstrated complete occlusion of the popliteal artery in all limbs (n = 24). The mechanical tourniquet achieved arterial occlusion after a median of 3.8 (3-4) turns, and 16 (12-20) seconds. No participants dropped out of the study because of intolerable pain, or any cause. Median pain scores for the mechanical tourniquets were 4.5 (3-7) (maximum pain) and 4.0 (2-7) (pain when locked). Median pain scores for the pneumatic tourniquet were 5 (2-6) (maximum pain) and 5 (2-6) (pain when fully applied). There was no statistical difference in maximum pain scores between the tactical mechanical tourniquet and the tactical pneumatic tourniquet (p = 0.75). No participant had any tourniquet applied for longer than 80 seconds., Conclusion: Both tourniquets completely occluded the popliteal artery in all participants within an acceptable pain threshold. Further testing is required before the presented tourniquets can be taken to the battlefield; particularly measures of self-application, and use on other anatomical areas., (Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.)