NGK spark plugs have been around for a long time, they are an original fitment brand you can trust. These not a lot to say about plugs unless you want boring copy and paste technical details, a new one will work that's the main thing. If you are having engine issues always start with the easier (and usually cheapest) fix it solution which will be a new plug. The Spark plug iridium SILMAR9A9S has a 10mm thread and 14mm hex drive, you will need a special thin walled socket to remove these plugs from the CRF 450.
If you hate been bombarded with unless crappy emails you should join our email list. Our marketing department is so overpaid and under worked you properly wont get any anything, but just in case you should join.