SD Cards – Not Recommended
SD Cards, while they have a write-protect switch, are actually no good for 
this purpose because it’s not actually hardware write protection – at best 
the card reader sends a signal to the operating system that the drive should 
be treated as read-only. The write-protect switch on the cards is read by a 
sensor that’s part of the card reader, and the card reader then passes along 
to the operating system whether the card is read-only. According to the 
specification from http://www.sdcard.org/:

A proper, matched, switch on the socket side will indicate to the host that 
the card is write-protected or not. It is the responsibility of the host to 
protect the card. The position of the write protect switch is unknown to the 
internal circuitry of the card.

Basically this means that either a) cheap card readers that lack the sensor 
or b) operating systems or malware that don’t respect the “please don’t 
write to this disk” flag can write to the drive. While this may not be 
likely, it’s also not as secure as you might think based on the presence of 
that switch.

"jo" <nerasyti@net.lt> wrote in message 
news:lsaf0q$2er$1@trimpas.omnitel.net...
> perkame USB SD kortelių mažą skaitytuvą, į jį dedame SD kortelę, kuri turi 
> apsaugos jungiklį nuo ištrynimo. Galima tą jungiklį užpilti klijų lašeliu.