They're available in 125 KHz, 13.56 MHz and 840-956 MHz variants, with chip options including HITAG 1/2/S, MIFARE Classic 1K/4K, I-CODE, and Alien/Impinj/Monza UHF chips.
They're made of ABS plastic, weigh about 3 grams, and measure 28x15x1mm for LF/HF or 36x24x1mm for UHF variants, available in black, red or blue (other colors on request).
Yes, logos can be applied via laser engraving or single-color screen printing, and serial numbers can be laser engraved for individual item tracking.