A DTF printer prints the colors in reverse onto clear film, followed by a white layer. While the ink is wet, a fine adhesive powder is applied, the excess is shaken off, and heat melts what remains into a glue layer. The finished transfer can be pressed right away or stored and pressed later, onto almost any part of a garment that fits under a heat press.
DTF needs no pretreatment and bonds to cotton, polyester, blends, nylon and other fabrics that DTG handles poorly. Prints are bright, opaque and detailed, including on dark garments. The trade-off is feel: the design sits as a thin, flexible film on top of the fabric, smoother and more noticeable than DTG or water-based ink, especially across large solid areas.
Ask how the transfers are pressed (time, temperature, pressure) and what wash care the transfer maker recommends, since poor pressing causes lifting edges. See DTF vs DTG and types of shirt printing.