“观察孔”用英语怎么说？

他们能够通过窗户(观察)孔监视左邻右舍.They could spy on their neighbour through a porthole window.在挡手护罩的挡手部分上还开有用于观察的 观察孔.A hole for observation is also arranged at the hand - baffle part of the hand - baffle protective cover....