Ekwenziweni kwezinto zokuvala kanye nemichilo yokuvala, i-PU (i-polyurethane) Imichilo yokuvala uphawu ithole ukunakwa okukhulu ngenxa yokuqina kwabo okuhle kakhulu, ukuguquguquka, nokuqina. Umugqa wokukhiqiza umugqa wokugqoka we-PU ophethe kahle ungathuthukisa ukusebenza kahle kanye nekhwalithi yomkhiqizo wokugcina, ukuyenza ibe yinto ebucayi yemikhuba yesimanje yokukhiqiza. Ukukhiqiza