I've used the Dunlap Straplok's for years...recently I tried the Schaller strap lock.  Both seem as sturdy as the other.  The Dunlop still uses an E-Clip to hold the hardware onto your strap while the Schaller has a threaded nut.  A toss-up between the two strap locks, but the Dunlop has never failed me and is a better priced locking unit.  Plus the Dunlop's are available in chrome, stainless and black to highlight your sweet axe!