Well back then the stem that was the top of bowl ..was layered from wide to smaller width then again to smaller width that matched the width of the glass shaft that went into the water screens came in 3 sizes in a package oppose to only 1 size width screens nowadays. As you know when heat to rock it melts and would drip to next screen and again to next screen (all seperated maybe 2/16 apart) and finally to glass shaft that we ventuslly went into bong and water. Water prevents rez. Anyway its a long ago method that pipes aren't made that way anymore. Wascsingle screen stages only torch flame hot enough to burn n melt as much as possible. Nowadays...lighters...but torch flame always better...!