The Dunlop Dual Design Straplock System is a sturdy, fairly easy-to-assemble and easy-to-install alternative to guitar straps slipping off of instruments.  The screws that are used to attach the Straplok to the guitar are heavy gauge and pretty large--there's little chance that these are going to come out.  The locking mechanism seems like it is secure and should require little maintenance.  The only disadvantage of the Dunlop system to Schaller's system is that the the Dunlop sticks out measurably farther from the guitar's body.  Ordinarily, it seems like this should be only the most minor of inconveniences.  On an instrument such as a Hofner "violin" bass, though, or any guitar with a strap button on the back of the instrument, this makes it difficult to hold the body of the instrument against your body for support.  Schaller's strap locks might look a little more elegant to some players.  The Dunlop Straplok System is sturdy, should provide a long life of service, and can be found at a better price than several of its competitors.  Recommended for most guitar body styles