The AVR64DD28-I/SO from Microchip Technology is an AVR DD 8-bit microcontroller Integrated Circuit running at 24 MHz with 64KB (64K x 8) flash, in a 28-SOIC package.
The AVR64DD28-I/STX from Microchip Technology is an 8-bit AVR DD microcontroller Integrated Circuit running at 24 MHz with 64 KB (64K x 8) flash, in a 28-VQFN (4x4) package.
The AVR64DD28-I/SP from Microchip Technology is an 8-bit AVR DD microcontroller Integrated Circuit running at 24 MHz with 64KB (64K x 8) flash memory, in a 28-SPDIP package.
The AVR64DD28-I/SS from Microchip Technology is an 8-bit AVR DD microcontroller Integrated Circuit running at 24 MHz with 64 KB (64K x 8) flash, in a 28-SSOP package.