Technics SP series mats?

Other recent discussion here discusses replacement mats for DD tables, including the SP series.  However based upon photos showing different ring patterns of stock Technics mats it seems there may have been a few different models over time.  The mat with my SP-10 Mk2A is SFTG172-01 while the mat with my SP-15 is SFTG015-01.  The ring pattern appears the same but the first one is heavier, thicker, and stiffer.

So does anyone know how many different mats were provided for the SP series and if any one is recommended over the others?  Perhaps more important, for those who have tried different mats did they offer sonic improvements over any of the stock Technics mats?  I realize this is difficult to answer unless someone tried more than one model Technics mat. 
I think Technics rubber mat must be replaced, i've had 2-3 different types. They are all bad. I remember how huge was the improvement when i first tried Micro Seiki CU-500 (2.7kg) on my SP-10mkII. Later i discovered SAEC-SS300 (870g) as a cheaper alternative, but also amazing mat for Technics SP-10mkII. The CU-180 (1.8kg)  is somewere in between. 
SAEC is the most affordable mat! But stock rubber mat is the worst ever. 
Not sure which Technics rubber mat I had with my SP10mk2, but also stunk. Every mat I tried instead was an improvement. I tried also the suggested modest priced mats I could borrow or buy including Herbie's Way Excellent II Turntable Mat, Funk Firm Achromat, the Boston Audio mat(mostly acrylic) which is the plastic one with the black raised dots that actually lifts the LP off the platter, a couple of spongy, vinylish ones that I don't recall brand and ultimately the copper and stainless steel mats that were head and shoulders the best on my table. I tried them all with 5 or 6 different center clamps & weights ranging hugely in design from the light & affordable Michelle to the heavy & pricey Stillpoints. For my money a $200 custom made 4kg SS 8mm thick mat and an old Micro Seiki center weight were the way to go. 
For the price the Herbie's mat was excellent, but if you get one be sure to order the proper diameter as there are versions just a bit to wide that interfere w/the lip on the edge of the SP10mk2 platter. Cheers,
S Bank, You actually put a 4 kg mat on your SP 10 Mk 2? The entire platter of an SP 10 Mk2 weighs something like nine or 10 pounds and of course 4 kg is nearly 9 pounds. so you doubled the mass that had to be driven by the motor and supported by the bearing. I don’t see how that could be a good thing, but of course it’s your turntable to do with as you wish.

Of course, putting a MS CU500 on a mk2 is similarly over the top, IMO. 
Lew, yes I did. Used it that way for about a year and a half before I sold it as I downsized for a relocation. Never had a problem. Our pal, dgarretson, gets partial credit / blame  :-) for helping me down that path.
Those who heard it heard how it could be a good thing. 
You can see pics here on the site of the man who made it.
I use a Herbie's Way Excellent II on my SP-15 and its significantly better than the stock rubber mat. Seems like it would be worth a try on the higher end decks too.

Why rubber?  Agree with above posters.  Try a Cu-180, Cu-300, AF Copper, Tenuto, Acrylic perhaps.  Rubber just deadens the landscape in my experience.