Indawo yokugcina uwoyela noma indawo yokungena uwoyela ixhumanisa i-injector ohlelweni lokugcoba oluphakathi, ihlinzeka ngowoyela wokugcoba ohlanzekile ngengcindezi elawulwayo.
Iyunithi yokulinganisa ilawula ngokunembile inani lamafutha alethwa ngomjikelezo ngamunye noma ngokujikeleza komshini ngamunye, iqinisekisa ukugcotshwa okuzinzile ngokusetshenziswa okuncane kwamafutha.