These are all made of extremely strong material for long lasting and durable use. they have a strong Velcro fastener to hold the ballast in yet is able to be used over again without the Velcro getting worn .with ease of fitting to put just the right amount of .These bags ALSO have a Double velcro seal not like most bags which only have a single seal! the pouches have been manufactured so as to leave a little room in for comfort around your waist. when the desired amount of ballast is used. all in all a well made quality product as you would expect from, AKM direct from Factory