I have two of these on my Pioneer TTs(PL-A45D & PL-112D). Look great and do what they're made for.

Works, is weighty. Warped records can be difficult to place or remove, so it is precision machined. Aluminium won't rust, and if your turntable is Japanese then it especially should have "Nagaoka AD-653" (slash two) spinning on it. Keep your plastic adapter, but this looks professional and keeps 45's aligned. Simple, unbreakable, all it should be, and cheaper than a few records at the thrift shop. If you've ever touched the anti-skid dial playing a 45, be sure to have a round adapter like this.

Good as and nearly identical as the Technics Sl-1200 adapter.