Are these expandable to 90 lbs?
No. 50lbs per dumbbell.
I think he meant are they compatible with the expansion pieces you can purchase up to 70 or 90lbs?
According to the Amazon listing these are not expandable.
PowerBlock Personal Trainer Set, 5 to 50 Pounds per Dumbbell https://www.amazon.com/dp/B000NWTX6W/ref=cm_sw_r_awdo_navT_g_Q0VF6MDTFNYTE4SKYSSQ?psc=1
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