sod Chambers. ...anyway, it's to BE contained, ie inside something.
"Main Entry: drill
Part of Speech: verb
Definition: bore hole
Synonyms: dig, penetrate, perforate, pierce, prick, punch, puncture, sink in"
penetrating works for me. maybe not great but i'e seen worse.
Brendan, i owe you a big apology, i meant nothing by the exclamation mark, but do see how it could have been misconstrued.