[JOINT FILING AGREEMENT This Joint Filing Agreement may be executed in separate counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same instrument. IN WITNESS WHEREOF, the parties have executed this Joint Filing Agreement on December 30, 2015. TRUSTBRIDGE PARTNERS III, L.P. LIN Ning David Authorized Signatory TB PARTNERS GP3, L.P.] [SCHEDULE 13D CUSIP No. 74734M109 1. Names of reporting persons. I.R.S. Identification Nos. of above persons (entities only) Trustbridge Partners III, L.P. I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) N/A 2. Check the appropriate box if a member of a group (see instructions) ¨ x (a) 3. SEC use only 4. Source of funds (see instructions) OO 5. ¨]