I am currently looking for one

I tryed some 2o pound ones but it was not very effective,

I tryed a 40 pounds one and it was way better

do you guys know some that may be good

brand etc

thanks in advance

not recommended

Look up hypervests? Never tried one but seemed like a sweet system.

this

bad for your joints

Depends on what he's using it for. For all we know he could just be looking for a way to increase resistance during pullups.

hes prob gonna bench and do curls with it

please don't run or walk distance with it.. i have to ruck 1x a week and my knees are already getting torn up.

Poor lower limb posture

ruck in poor terrain with 50lbs on your back, once a week for ~year and a half. Let me know how it goes

No I think the army is a dumb institution. Doesn't change the fact that I bet if you learned how to use your legs properly and ideally you would minimize a lot of damage to your joints