The caisson should be made of high quality and from environmental materials, with the purchase you should check the availability of documents, certificates, warranty obligations, GOSTs, etc.
Ka-joojinta waa in laga sameeyaa tayo sare iyo qalabka deegaanka, iyada oo la iibsanayo waa inaad hubisaa helitaanka dukumentiyada, shahaadooyinka, waajibaadka damaanad qaadka, GOSTs, iwm.