The bargaining solution among threshold strategies

We consider a bargaining problem which engages a seller (player $I$) and a buyer (player $II$). Each player possesses private information about own reservation price which is unavailable to the opponent. Players appear on the market and announce their prices for a product. If the transaction takes place then the gain of a player is the difference between the negotiated and the reservation prices. We find the equilibrium in this game among threshold strategies