Testing a couple of hygrometers I bought from Amazon using Boveda packs before adding to my humidor. Let me know if you have any questions in the comments.
I do not make any money from the following links for your convenience.
Round hygrometer: www.amazon.com/dp/B07WJJ9265?ref=ppx_yo2ov_dt_b_product_details&th=1
Rectangular hygrometer: www.amazon.com/dp/B07QMZL448?psc=1&ref=ppx_yo2ov_dt_b_product_details
Boveda test kit: www.amazon.com/dp/B000A3UBLA?ref=ppx_yo2ov_dt_b_product_details&th=1
Boveda 49% humidity pack: www.amazon.com/dp/B076H4SY2D?ref=ppx_yo2ov_dt_b_product_details&th=1