Adapter shock absorber SIP Performance PX/T5, front, Art.No.72000FA

I recently bought the above part and am a little mystified as to how and where it fits? I have stripped the shocker down and removed the spring but was a little unsure as to how far to go without releasing the gas or breaking anything (or losing an eye). If anyone could offer some advice I would be very gratefull. Thanks, Jimkerruk.