pToken contracts are tokenized versions of leveraged long or short positions on an asset. pTokens are minted by sending ETH or another asset into the pToken contract, which in turn borrows from an iToken lending pool, does a Kyber swap, and sends the user back an equivalent amount of pToken (ERC20) at the current pToken price. For short positions, such as 2x short ETH, the pToken borrows from the iETH token, then swaps that ETH for a stable asset (DAI) on KyberSwap. For long positions, such as 2x long ETH, the pToken borrows from a stable asset, iDAI, and swaps that for ETH on KyberSwap. The tokens are perpetual, but positions are not. If a position loses too much value, or reaches the end of the loan term (28 days), it will be liquidated and a new position will be opened behind the scenes. Traders should be aware of the liquidation price of the pToken, and burn their pTokens prior to being liquidated, to avoid locking in any losses.