I bought these adapters while doing a mass conversion of my house to LED bulbs. They worked well and allowed me to substitute 11 watt (60 watt equivalent) LED bulbs for the dim, disgusting, expensive 40 watt incandescent E17 base bulbs that were in the fixture. Why anyone in the U.S. would install a fixture using E17 bulbs escapes me, but that is another matter.During installation, one of the sockets in the four bulb fixture would not work with any one of the five adapters, while the other three sockets worked fine with any of the five adapters. Clearly the problem was that either (1) The foot contact on the adapter was not long enough to reach the hot contact in the E17 socket, or (2) The hot contact in the E17 socket was crushed down too far to permit the foot contact of the adapter to reach it. I solved the problem by using needle-nosed pliers to bend up the hot contact of the E17 socket slightly, and then the adapter worked fine. Obviously you should not try this unless you are absolutely certain that all power to the fixture has been shut off by turning off the switch and turning off the circuit breaker (or removing the fuse) that controls the fixture circuit, and taking the other usual safety steps appropriate to electrical work. If you don't understand what these are, do not try it. You could electrocute yourself.