T-Mobile USA Website when you use the promo code SIM99 at checkout.
When they aren't on sale, T-Mobile SIMs are a ridiculous $15 each, so you might want to stock up now for future use.
The prepaid phone 3-in-1 SIM Starter Kits include a nano SIM with mini and micro adapters and an activation code.
The activation code is required when activating a new line of service on any T-Mobile prepaid phone plan, including the $30/month 5 GB of data, unlimited messaging and 100 minutes plan, which is only available with new online activations.
If you have a tablet or mobile broadband device, these SIMs can be used to activate a tablet or hotspot on any T-Mobile Prepaid or postpaid Mobile Internet plan. They also let you activate a supported tablet on T-Mobile's Free Data for Life plan which comes with 200 MB of data per month absolutely free.
Prepaid SIMs can also be used as replacement SIMs for any T-Mobile account, postpaid or prepaid.
There's a limit 3 SIMs per per order and 5 SIMS over a period of 30 days.
I'm disappointed that T-Mobile has switched from selling individual SIMs in mini, micro and nano sizes to using adapters which have a history of damaging phones. Maybe the adapters T-Mobile is shipping are better than than the ones that broke phones, but I'm very wary of using an adapter in any phone where the SIM slides into a blind slot.
Prepaid Operator Profile: T-Mobile
Is Your Tablet Eligible For 200 MB of Free T-Mobile Data Every Month?