Walmart.com hasa 20-Treatment 3D Professional Effects Twin pack (40 treatments) available on their website for 44.88 (normally 89.94). Shipping is free.
- Professional Effects are Crest’s "second-best" white strip treatment option (second to their Supreme Flexfit).
- Crest suggests that you can use up to two boxes over the span of a year. So using one box up front followed by the second after six months time can maintain whitening.