These are stabilised chlorine granuals used to to keep hot tubs and swimming pools clean.
It was a 5kg tub but I would say more than half left in the tub.
I paid £35 from amazon but my hot tub is now gone so I'm offering for free!!
Pick up from Ifield
Chlorine Granuals for hot tub/pool (Crawley RH11)
This offer has been gifted to someone and is no longer available.