Concentric - Symmetric Casing system idapangidwa mwapadera kuti ibowole ndikubowola dzenje nthawi imodzi kudutsa malo osakhazikika.Dongosolo la dalaivala lophatikizidwa ndi mphete yokhutiritsa kapena mphete yogwiritsiridwanso ntchito imapanga mawonekedwe amutu athunthu omwe amawongolera kwambiri kuchuluka kwa malowedwe ndi kubowola kuwongoka.Ma grooves amkati amkati pamodzi ndi nsapato zomangidwira mkati amapereka chisindikizo chabwino ku batani la dzenje lobowola, motero kuchepetsa kusokonezeka kwa kuzungulira kwa dzenje lobowola.