I've got a whole bunch of those military fiberglass sections and find them to be
totall unsatisfactory if you want to go more then eight fee up with them. They
do not make a snug fit, they are not a standard size, they have no attachments
for ropes etc., etc. I would recommend using something else.
Tom
Tom Brennan KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html