Ultra-Small UHF RFID Tag Rain - 10 Pack - KIT-16464 - SparkFun

These tags operate in the UHF (865MHz to 928MHz) band and contains a 96-bit EPC field that is programmable by the user.

UHF RFID Ring Antenna - SPX-15113 - SparkFun Electronics

Ultra-Small UHF RFID Tag Rain - 10 Pack - Proto-PIC

From Ideation to Innovation - News - SparkFun Electronics

Sensors - Page 1 - Proto-PIC

RAIN RFID Reader Modules: Impinj-Enabled, Partner-Built

, The 'Rain' ultra-small UHF RFID tags from Murata are really exciting because of their fantastically small size -- they're just a 1.25 mm square

Ultra-Small UHF RFID Tag Rain - 10 Pack

UHF RFID Ring Antenna - SPX-15113 - SparkFun Electronics

RAIN RFID Reader Modules: Impinj-Enabled, Partner-Built

Ultra-Small UHF RFID Tag Rain - 10 Pack from MindKits New Zealand