This training manriki is a good bit of kit. I had one in my training bag when I was in the Bujinkan and a lot of the guys asked about it. Also known as a kusarifundo, it is hard to find good ninjutsu training weapons online and this is one of the best. Most training kusari found for sale online are made of knotted rope.

I once modified a set of these to make another ninja training weapon. I simply drilled a hole through the bottom of a plastic kama sickle and fitted a key-ring hoop, then fastened the manriki onto it and then made an excellent training kusarigama.

The only down side to this manriki as it is, is that the plastic chain can be a bit weak and break easily. However, it's easy to find a length of suitable metal chain in your local hardware or DIY store and just add the foam end-pieces to that.