These can be filled with sand or lead shot or even dirt if you’re desperate.
They are a pretty cool idea but unless you want to be weighing, emptying and refilling your kettlebells depending on what exercise you are doing you are better off buying a range of sizes.
I will tell you what the experts recommend in terms of kettlebell sizing later but for now I would not buy a hollow kettlebell and feel that they are somewhat of a gimmick.
Personally I like training with a goal and progressing towards that goal each session, using a hollow kettlebell makes this harder then it needs to be.
For some I understand that these may be a great option if you have very limited space or spare bags of lead shot lying around but for ease of use and accuracy of weight they are not for me.
This brings me to my next good reason not to buy the cheapest kettlebells you can find
How looks can be deceiving (Page 6 of 7…)