Abstract: A clip for retaining thin plastics film material (6) in tension formed of a pair of elongate channel members (2,4) removably assembled together in inverted relationship. The film material passes through the fixing between opposed cooperating complementary sinuous surfaces (8,3;9,12) of the flanks of the channel members and in so doing passes over surface portions of the fixing at the entrance to the cooperating surfaces of each flank pair, which are exposed to direct radiation. To avoid degradation of the plastics at these surface portions, means (30,32) are provided on one of the channel members to cover or shield these surface portions from such direct radiation. The covering or shielding (30,32) may be integrally formed with one of the channel members of removably afixed thereto.