Audio Technica AT 666 vacuum disc

Is anyone currently using it?
I have it on trial, the product is almost perfect NOS, but after about 7-8 minutes the LP loses its vacuum; is it necessary to also use a clamp to get the vacuum for the whole LP?
@lewm : In this link please go to my last post and in the link down there download the 82-83 catalogue:

and look the pdf 22 page where you will know on that 666 item.

I had the AT-666 when it was first released in the '80s. The rubber seals were new: they hadn't aged, as they surely have by now if using an old one. Even then, the vacuum was dodgy: it held securely for my Rock records, and I could pick it up with the LP still clinging to it at the end of play.

The vacuum failed on many Classical records. That's not a joke, of course it wasn't the music – Classical works tend to run longer, giving more time for the suction to escape.
It still served its purpose – the worst warps are at the rim, that's where the stylus rides like a surfer. By the time it reaches the lead-out groove, the vinyl is pretty much flat. The 666 held them down as long as the record was playing. Long enough. And on a badly warped record, it was dramatic: all warp-wow eliminated.

I didn't use it much: a) too much hassle, b) most of my vinyl didn't need it, and c) I didn't listen hyper-critically all that often.
I sold it in mint condition to a guy who ran a service digitizing people's old LPs. He called me, furious, complaining the vacuum didn't last the length of the record. I offered his money back, but explained that it lasted long enough to get past the distortions, and he was giving his customers what he'd promised. I suggested he keep it a few days, check the results, and then decide. He did and called back; he was keeping it, and apologized for his outburst.
The 666 was an imperfect solution but still a very useful accessory, if you need what it does. It's also very well-made and certainly worth its cost... if you need it

I don't have much hands-on experience (only at shows and an audio shop or two), but here are two similar products made today:

kind regards, jonathan
Jonathan, Thanks for that information.  If COVID ever permits me to visit Tokyo again, I will look for one of those two accessory mats.  Are they readily available in Akihabara, like at Yodibashi Camera?

Also, I want the P3 shown in the teq advert.