Thats the knock-off and you dont want it.
https://www.amazon.com/CAT-Combat-Application-Tourniquet-Time-Stamp/dp/B01ITAKG6A/
I've had a number of safety and first aid courses. Everyone who is a professional, whose actually used these things tell me you want the name brand version. Not the cheap one.
Also consider an israeli bandage and some large sterile pads. And medical tape and scissors of course.
Can you use Amazon.co.uk?