are provided at each end of the rings 24a and 24b to connect the rings together such means is in the form of a mounting block 40 having a threaded aperture 41 provided at one end of the ring at the top of the ring 28 on the inside surface of the band 30 and a mounting block 42 including a bolt 43 provided at the other end of this ring at the top of the ring 28 inside of the flange 30 the two rings 24a and 24b are then connected by placing the block 40 on one ring in alignment with the block 42 on this other ring with the bolt 43 in position to be threaded into the threaded aperture 41 the bolts are then turned to draw the two rings into tight engagement with the mounting flange 17 on the frame 14 prior to mounting the frame adapter 20 on the frame the compressable seal strip 46 is applied to the inside surface of the ring 28 the strip 46 can be formed from a rubber gasket or a mastic such as kent seal no 2 when the adapter 20 is mounted on the flange 17 the compressable material will be squeezed into the space between the ring 28 and flange 17 the legs 34 and 36 of the bands 32 maintain a space between the flange and the ring so that the compressable material 46 will not be squeezed out of the adapter the sleeve 18 is secured to.