There is also a "rip-off" version from Asia, you can see it here.
http://www.speargun.com.au/spear/han...grip/index.htm
The trigger mechanism is of the friction type using in a sense a tilting washer, although here it is more of a metal ring or band. Pulling the trigger straightens the ring up so that the polespear can slide right through it. This is virtually a clone of the "Sea Hornet" sliding grip handle which was also offered for a time by AB Biller in the USA.