Yes. You can use both SYB Air Tubes and SYB H.A.R.D. together, as SYB Air Tubes is a standard headset (with the additional benefit of EMF protection) that has a 3.5mm audio jack.
However, doing so may not be required as these products are alternatives to each other, and they do the same thing, i.e., stop EMF emitted by your phone from reaching your brain through the wired headset channel.
Both SYB Air Tubes and SYB H.A.R.D. are perfectly capable of providing you protection from the EMF being transferred by your phone to your brain.
And using these two products together may negate one of the benefits of our SYB H.A.R.D. which is the ability to shield EMF radiation without sacrificing audio quality.
If you have any additional questions, reach out to our customer service team at hello@shieldyourbody.com.