Transcend 128GB microSDXC 300S Memory Card with adapter, Class 10, U3, V30 - £5.34 @ Amazon

Nice one! Never saw a low price like this before for a 128 gigs card in this speed class.
Speed Class UHS Bus Interface
UHS-I provides faster bus speed using just one row of pins, while UHS-II uses two lanes for even faster data transfer via two rows of pins. The symbol "I" means UHS-I, and "II" means UHS-II. Please make sure your device supports the same standard to benefit from the increased speeds.

‌ UHS Speed Class
UHS Speed Class includes UHS Speed Class 1 (U1) and UHS Speed Class 3 (U3). UHS Speed Class 1 supports a minimum 10MB/s write speed, whereas UHS Speed Class 3 supports at least 30MB/s write speed.

‌ Video Speed Class
Video Speed Class is defined to answer a demand for high resolution and high quality 4K8K video recording. V60 (60 MB/s) and V90 (90 MB/s) can support 8K resolution, while V6, V10 and V30 capture high-definition and 4K resolution and ensures a minimum sequential write speeds of 6 MB/s, 10 MB/s and 30 MB/s respectively.

‌ Application Performance Class
Application Performance Class assures minimum random and sequential performance speeds to run and store smartphone apps. Application Performance Class 1 (A1) delivers minimum random read of 1,500 IOPS and random write of 500 IOPS. Application Performance Class 2 (A2) delivers minimum random read of 4,000 IOPS and random write of 2,000 IOPS.