Fender strap locks, which are made by Schaller in Germany, are standard on some Fender guitars and basses, and you can buy them from Fender dealers. The strap locks are attached to the guitar strap and clip over special strap buttons on the guitar. The strap buttons keep your strap from coming loose and prevent accidental dropping of the guitar. Installation takes less than 10 minutes, and requires common hand tools.
Remove the existing strap button from the guitar by inserting a screwdriver into the strap button and turning it clockwise to remove the retaining screw and strap button.
Install the strap lock strap button on the guitar by placing the screw into the button, and screwing it into the existing screw hole with a screwdriver. If the strap lock kit comes with a felt washer, slip the washer over pointed end the screw before installing.
Unscrew the nut from the strap lock by turning counterclockwise, and remove the nut and washer underneath.
Insert the strap lock into the strap hole by pressing the threaded section through the holes on the underside of the strap.
Place the washer over the threaded section of the strap lock and install the nut onto the threaded section, turning it clockwise until the nut is hand-tight.
Tighten the nut fully with a pair of pliers, turning the nut clockwise while holding the strap lock in place with your other hand to keep it from turning.
Repeat all steps to install the second strap lock.
Clip the strap lock onto the strap button while pulling out the retaining pin on the lock. Releasing the retaining pin will lock the unit in place.
The strap lock section that attaches to the strap button is "U" shaped. For best results, install the lock on the strap with the "U" facing upward. This will allow the strap button to rest in the bottom of the "U" for added security. Periodically check the tightness of the nut and the position of the "U." Over time, the nut may become loose, causing the strap button to shift.
If you're using a new strap, the strap locks may be difficult to insert into the hole. Do not cut the hole wider, as the strap material may tear over time. Carefully work the lock through the hole by turning it and it will eventually insert. The strap lock button is only meant to hold straps with the locks installed, and may not securely hold a strap without locks due to the slimmer button diameter. Using a strap without the locks may cause it to fall off the button and cause the guitar to fall.