PROLOGO DIMENSION TRI NACK 143 BK/SLNew V Shape base paired with a wider tip and larger seating area improve comfort and overall performance Variable density foams throughout further improve long term comfort and reduce pressure especially while in an aerodynamic position PAS features a channel in the seat to alleviate pressure and numbness in the pelvic region by promoting healthy perineal blood flow Nack models feature a Nano Carbon composite rail paired with reinforced seat clamp