Best magnetic numbers/class letters?

About a decade ago, I bought a set that lasted me forever and ALWAYS stuck.  A few years ago, they finally gave up the ghost.  The last two sets I've purchased have either gotten stiff/brittle and stopped conforming to the doors or had weak magnets and disappeared off the car at a high speed autocross.  I prefer individual numbers/class letters because Kazoo Jr. and I usually codrive.  We basically sign up at "91" and "61" and flip the "6/9" every time we change drivers.

The Mrs. wants to get me a new set for Christmas, so:  What do you all recommend?

I have a set from Autocross Digits and have been pretty happy with them. 

I've been using a set of basic ones from these guys for 2 years.  Still holding up well and have made a 2 hour trip home at 70 still attached to the car.  https://www.izoomgraphics.com/ 

I have 3 sets from Autocross Digits for various cars and love all of them. Can't recommend them enough.

Trackdecals.com has supplied mine for a few years now.

I have glued small disc shaped rare earth magnets to my numbers. This is part of a set that I made from some magnetic sheet that I bought from Granger.

The paint is spray paint made for vinyl.

I've been getting numberboards made from magnetsonthecheap.com and they haven't failed me at autocross. I've left them on while driving on the freeway and they held fast. Note they are a printed large magnet and not just numbers, the quality is "decent"... but they were cheap. You could easily cut them to made the numbers you want.

I have had good luck with the rectangular car magnets from Vistaprint.  They stay on the car for 2 hour round trips to autocross 10+ times a year.  They also stayed on during a time trial at ~130mph.

I have used FireStormGraphix.com for several years and always a great product. They also support Grassroots. https://firestormgraphix.com/vinyl-scca-nasa-race-car-numbers.html

I used to go with https://soloperformance.com

but now I have a vinyl cutter and just buy magnetic sheet on Amazon.

Still making my own. I'm using black shelf liner instead of paint now. 
These are my new numbers that we made last month. 

I made new class letters last night. 

I don't have numbers, but I do have various decals on magnetic vinyl to put on my cars. I buy the magnetic heater vent covers from Menards. They're about a perfect size to put an individual number on though.....Deflecto Magnetic Vent Cover - 3 Pack at Menards®....$7 for 3 pieces 15"x8".

...and we all replied to a necrothread....