Yintoni umahluko phakathi kweerivethi ze-countersunk head blind kunye neerivethi ze-round head blind?

Iirivethi ezingaboniyo ngentloko engqukuva azidingi kuxutywa, ziya kuphuma kumphezulu emva kokuxutywa, ngelixa iirivethi ezingaboniyo ngentloko engqukuva kufuneka zixutywe nge-120°, kwaye ziya kuba kwindawo efanayo nepleyiti emva kokuxutywa.