Somebody asked him this at DCC in '07 and Efren said " soaked Elks". I'm assuming he meant some type of milk-dud.
They are soaked and pressed .
He showed two pieces to me at Hard Times one time.
He brought some of his own.
He had one tip replaced locally and he said he thinks the local repairman did not use the one he gave him.
He also told me and a late friend over late lunch in Manila about his infamous $15 cue. He won that cue in a match. He started using it as a break cue then the tip settled and he liked it so much, he started using it as his playing cue.
He basically started liking pressed or settled Elk Master since.