L-Pads: 4ohm or 8ohm?

Hi, I need help because I don't understand ohms very well.  I have a 50W per channel 4ohm amp and 4 ohm MB Quart speakers with separate tweeters.   The tweeters are too close to my head in my car and too loud (even after using the -6db setting with the crossovers), and I want to get L-Pads to turn them down a bit.  My question:  do I need to get 4-ohm L-pads?   Or can I use 8ohm L-pads?  I can only find one place online that has the 4-ohm ones (partsexpress.com) and everyone else has the 8 ohm variety.    Will there be harm to my system or degradation in sound qaulity if I use 8ohm L-pads for my tweeters?  ---- thanks for any help you can give me. 

I have a pair of those 4 ohm L-pads, and they were the only ones I found, also.  They are much bigger than I anticipated them to be when I ordered them.   About 2 1/2 inches deep not counting the stem (knob), and about 3 1/2 inches in diameter.  They are tucked away under the rear deck of my car and are wired to the rear speakers, and although I have added an amp and could go without using them now, they work for attenuating the rears really well and are permanent.  Make sure you have locations you can put these in, and drill a hole for the stem and knob for adjustment.

I suppose you have tried redirecting the axis of the tweeters so that the sound is not so direct?