This is a PP material pipette or dropper. The closure size is 18mm TE, it has a protective ring below the closure part, we also call it tamper evident pipette.
Pipette MW4-9 is a good option for the PET bottle neck.
Fit PET Bottle
18mm Tamper Evident Closure (18mm TE Cap)
closure color and bulb color can be customized
dip tube options
glass dip tube and plastic dip tube options
glass tube length can be customized