Use these shortly after buying them. Because MC GC numbers can be hacked. and then drained of funds without you knowing about it.
It used to be that the MC GC were a different company than the VISA GC at Staples. I think they were USBank IIRC where the VISAs have always been Metabank.
Since Staples switched to Metabank for the MC GCs, it is my understanding that neither have problems. Please CMIIW! In any case, I have never hade a problem with the Meta MCs, only the US Bank ones.