Squirt SEAL sealant
Recommended by Syd and Macky
Squirt's tire (or as they spell it, tyre) sealant uses microfibers and their proprietary BeadBlock granules to seal holes up to 1/4" (6mm). They also offer these nice pouches that make it super easy to top up your sealant without breaking the tire bead. Discount code below.
The rest of this recommendation is only available to paid members.