Makampani khumi apamwamba ku China, okhala ndi antchito 1200, adapeza zinthu 31 zopangidwa ndi ma patent 9. Zipangizo zopangira zapamwamba, zida zotenthetsera kutentha, zida zowunikira. Njira zonse kuyambira zopangira mpaka kumaliza zidachitika m'nyumba, gulu lamphamvu la uinjiniya ndi gulu labwino kuti likwaniritse zosowa za makasitomala.