ORIGINAL: rewired
The large black o-ring on the nozzle is there to give your fingers something to grab onto when you're pulling that nozzle out. I have that same cap from Slimline, works very well.
Do you still have the orig packing? Look under that cardboard flap that's stapled to the bag it ships in, the assembly instructions are on a small piece of paper attached to the underneath of it.
Thanks for the info. I still have everything so I can send it back. However, there are no instructions on the cardboard packaging. Thanks.