referring to fig1 - 4 , a drum 10 has a cylindrical shell 11 with a drum head attached to the upper annular end portion 11a of the shell . the head includes a thin sheet 12 stretched over the annular edge 13 of end portion 11a , and a lip 12a of the head is carried by a tension ring 14 extending about shell end portion 11a . a retainer ring 15 is provided and located to urge the tensioner ring 14 in a downward direction in fig3 . the retainer ring includes an upper annular wall 17 , a lower annular wall 18 offset from wall 17 , and an intermediate stepped portion 19 between walls 17 and 18 . the stepped portion 19 has a lower shoulder 19a seating on tensioner ring 14 for urging ring 14 downwardly , in response to tightening of tensioners 20 spaced about the shell and urging ring 15 downwardly . tensioners 20 include rods 21 that are adjustable to adjust the downward force exerted by ring 14 . as shown , a tensioner flange 25 seats at 26 on the upper surface of ring 15 , and on the top of a finger 35 , and as the associated rod 21 is rotated in one direction , the flange pushes downwardly at 26 . that seating surface may be knurled to enhance friction grip of the flange to the seat . note the threaded lower end portion 27 of the tensioner rod , that engages threads in a lug or protrusion 28 attached at 29 to the shell . a lower tensioner rod 30 exerts upward force on a lower retainer ring 31 corresponding to ring 15 , for adjustably tensioning force exertion on a lower drum head 32 corresponding to upper head 12 . in accordance with the invention , fingers 35 are integral with retaining ring 15 , and project outwardly , and also circumferentially , to form j - slots 38 . the locations and spacings of the slots are such as to enable them to simultaneously receive the tensioners 20 as the ring 15 is adjustably rotated about the axis 40 of the drum shell , after the ring shoulder 19a is seated on the tensioner ring 14 . see in this regard fig5 showing ring rotation in direction 41 , causing slot 38 to approach tensioner rod 21 , which is relatively displaced out of notch 50 by cam surface 51 , in response to ring rotation . rods 21 are initially received in notches 50 spaced about the ring , when the ring 15 is placed on the shell . in order to allow selective travel of tension rods toward the slots , the ring lower wall 18 has its outer surface at 18a positioned to closely pass rods of different diameters , as are commonly used with different drums . for this purpose , wall 18 thickness t 1 at a region leading toward the entrance to slot 38 may be reduced relative to the wall 18 thickness t 2 at a region at the opposite side of the slot , as shown . it will be noted that the fingers 35 have lips 35a projecting circumferentially , as shown , and that they have tapered end terminals , as are provided by tapered surfaces 35b . it is found that such terminals can assist in guiding the tensioner rods relatively into the slots 38 . as referred to , an important feature of the invention concerns the provision of relieved zones , such as notches 50 on the ring periphery , as in wall 18 and in stepped portion 19a to pass the tensioners endwise upon ring 15 assembly to the drum . at that time , the retainer ring 15 is positioned in rotatably offset or displaced relation to the tensioners 20 . see in this regard fig5 showing the tensioner 20 received in the notch 50 . the notches are sized to receive tensioners of different diameters , as referred to above . cam surface or ramp 51 on the notch wall 52 acts to cam the tensioner rod relatively out of the notch , for sliding along wall outer surfaces 18a toward the finger formed slots , as the ring is rotated . fig8 is like fig5 except that the notch or notches 50 in lower ring 31 are offset toward the slot or slots 38 sufficiently as to be spaced from the strap 60 which extends between the throw - off device 61 ( see fig7 ) and sounders that are retained adjacent the lower drum head . see u . s . pat . no . 5 , 616 , 875 . therefore , the tensioners 21 do not travel past or over the strap 60 during ring 31 rotation to relatively displace the ring and tensioners , causing their entry into slots 38 . fig9 shows a tensioner flange 25 seated on the top surface of the finger 35 and on the adjacent ring wall surface . fig1 - 6 shows the preferred form of the invention . the ring 15 may consist of molded plastic material , or die cast zinc , or aluminum , or composite materials , for example . the term &# 34 ; ring &# 34 ; as used herein refers to a continuous ring and also to a discontinous ring , as for example a c - shaped body with a split between its opposite opposed ends . such ends may have an aligner holding them in alignment , or they may slidably interfit , or guided interfit . such a split ring can be discontinuously adjusted to better fit slightly different diameter drum heads .