HALO SleepSack Wearable Blanket The HALO SleepSack Wearable Blanket is the only blanket on the market this customized to fit a range of sizes to ensure safety for all infants.  Its design is making consumers and vendors alike rethink the idea of a baby blanket.  The SleepSack is the safest, yet softest blanket on the market.  It is made of  flame resistant micro-fleece. The SleepSack from HALO is sleeveless to reduce the risk of baby rebreathing into the sleeve.  It reduces the risk of overhea.