Sea To Summit Delta Core-V Self-Inflating Seat? Description The Delta SI V Seat is a compact companion offering foam filled comfort to any adventure. Whether providing much needed cushioning for aching glutes at the end of a long day, compensating for cold uncomfortable stadium bleachers or to soften the threadbare seats of a chicken bus in Central America, this is a welcome addition to your purse or backpack. Tough, 75D polyester fabric on the base and upper surface means it will go the distance.