This extension model PW3300 and PW3310 are only for use with the AR brushes and surface cleaners. The only wand extension we carry that can be used with AR brand pressure washers and will accept the existing spray wand from the machine is a model # PW3082860. This extension is 15 inches long and multiple extensions can be connected together if needed. Just keep in mind, the longer you go, the more pressure loss you would notice. With just adding 1 extension piece, you would not have to worry about losing any pressure at all.
I am posting a link below to this product on our site:
AR 15 inch Extension