auto glass shops have this sticky black sealant they use for windshield installation. they also use it to stick the rear view mirror on the windshield. it should cost you P50.00 if you bring it to them. be sure that the windshield and the base of the mirror is clean when securing it in place. detach the rear view mirror from its base prior to installation so as not to put weight while it is still not cured. when i did mine, i cleaned the windshield portion to attach the mirror and base of the mirror with denatured alcohol. wait a few minutes for it dry and applied sealant on the base of the mirror and stick it to the windshield. held it in place for 2 minutes and let go. waited 3 days for it dry and cure. finally, i attached the mirror to the base. 3 months passed and still in tact. another solution which would cost you some money is to order the real adhesive on amazon.com. it is called rear view mirror adhesive kit.