Ntoo ntsia hlau yog dav muaj nyob rau hauv tag nrho cov chaw hauv tsev thiab cov khw muag khoom kho vajtse thiab tsim los koom nrog ob daim ntoo ua ke.Lawv yog threaded ib feem ntawm txoj kev thiab ces muaj ib tug du shank rau saum.Qhov no pab tuav cov screws nyob rau hauv qhov chaw.Lawv kuj pheej yig thiab tuaj txhua yam ntawm txoj kab uas hla thiab lub taub hau duab.