A mount with DV (swivel) top and "DV" connection underneath.
By adding a "3/8 to DV adapter" (C52) you can use this mount to angle the antenna (eg for mounting on a sloping surface).
The mount has a good rubber seal and the use of a DV plug means the coax comes out at a right angle (ie parallel with the body) rather than straight down.
Remember to order a wingnut/bolt to go with it if you need one!