straight-hole downhole motor
straight-hole turbodrill
circular hole with periodic straight cracks
elliptic hole with a straight crack
elliptic hole with two straight cracks
straight button hole machine
straight-end button hole lockstitching machine
A shrinkage method combining with medium-length hole and shallow hole
electron-hole liquid drop (=electron-hole droplet)
hole by hole blasting technique
hole by hole detonating
hole by hole initiating
hole by hole initiation