Will this fit in a Sleepypod Air?

Yes the Small Blue DryFur fits SleepyPod Air very nicely, for your reference the 3rd picture down on this page shows the pad inside a White SleepyPod Carrier.

My carrier is: 20 x 11.5 x 12 , should i get a med or large? (will the large flex enough to fit? I'm afraid I won't have full coverage w/med)

If your carrier is a soft carrier the small will be the very best fit. Large and Medium are for hard sided plastic carriers.

Is this compatible with this carrier? i see the dimensions are bigger, but not sure if it folds? https://www.amazon.com/gp/product/b07zppsr2l/ref=ask_

You can always cut the pads to fit. They fit fine in this carrier- we removed the faux shearling liner first so Otis would have some headroom. ; ) https://www.amazon.com/Smiling-Paws-Pets

Yes the entire pads is 19.5" x 12.5". These DryFur pads feature a 2" flexible edge so they can flex up allowing the pads to fit pet carrier floors up to 19.5" x 12.5" or as small as 15.5" x 8.5" when sides are flexed up.

Brand	DryFur
Capacity	1 Pounds
Net Quantity	2.0 Count
Recommended Uses For Product	pet
Colour	blue
Number of Items	2
Item Weight	454 g
Item dimensions L x W x H	49.5 x 31.8 x 2.5 Centimeters
UPC	643345804317
Country of Origin	USA
Item part number	DF-100-2PK
Product Dimensions	49.53 x 31.75 x 2.54 cm; 453.59 g
ASIN	B06Y46SFN8

DryFur Pet Carrier Insert Pads Size Small 19.5" x 12.5" Blue - 2 Pack

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