These Mics can be made Cardioid...You just have to put in a different Capsule but it is much harder to find a good Low noise cardioid Electret Capsule at a Good Price point but Transound does make a few Good quality Low noise Cardioid Capsules but they are at least $7-$10 each but many have as Good of a Frequency responce as the Omni Capsules and have an even higher SNR....
If anyone is interested in some Uni-Directional (Cardioid) capsules you can get them here: