after suffering thru two iterations of shoddy chinese made tube brands, i finally found tubes that last for aggressive riding on dirt and rockstubes are holding air very well in the 2 months i’ve been riding in the mts back of my house; reminds me of the tubes i used to use in the distant past, before tubes were mostly slapped together in sweatshopsnow, the big question is how well they do over time, especially with no punctureswhy? last two brands i tried basically lost their integrity in the rubber; also, i bought a box with bad valve joins to the rubberUPDATE: tubes still holding their integrity after 40-50 rides on dirt ....... nice!