3. Chubu cha Elliptic: chubu cha elliptic ndi chinthu chatsopano chomwe chayambitsidwa m'zaka zaposachedwa. Poyerekeza ndi chubu chozungulira, chubu cha elliptic chili ndi kukana kwabwino kwambiri kwa kupanikizika. Komabe, chifukwa chubu cha elliptic chomwe chilipo chimapangidwa ndi tepi yolimba, mphamvu yake yolimbana ndi dzimbiri ndi yotsika poyerekeza ndi chubu chozungulira.
4. Chitsulo cha Mbiri: chimagwiritsidwa ntchito pamwamba pa nyumba yobiriwira yanzeru kuti chipange chimango chachitsulo. Chili ndi ubwino wotsika mtengo komanso kukhazikika kochepa poyerekeza ndi chitoliro cha sikweya. Chimagwiritsidwa ntchito makamaka m'malo omwe ali ndi mphamvu zochepa komanso chitetezo chochepa cha dzimbiri.