Barb, to be honest, I can"t remember if riser kit had had a 2nd hole . After installing them , I was not worried about stability . The risers seem quite durable and have had no problems with them at all . When I sit in passenger seat I don"t feel like I'm in a hole . As far as warranty goes , someone said that it would not void warranty . There are two sites on this Kona forum regarding seat risers .If you see some of the pictures that other owners have used for so-called homemade riser kits .you will be happy with the srautoshop risers .