Pick the correct top plate for your device.
RL-501 - Humminbird 300-700
RL-502 - Garmin GPS MAP 400-600 / Echo 100-550 / Echo Map 50s/ Raymarine Dragonfly Original & Dragonfly7/ Garmin Striker 4 & 5
RL-503 - For Lowrance Elite 5 / Mark 5/ Elite 4
RL-504 - Check Compatibility For Raymarine E7/ E7D + Lowrance HDS-5 / HDS-7 (Gen 1 and 2), Lowrance HDS-9 (Gen 3) and Lowrance Elite 7, 800 and 900 Humminbird Series, B&G Zeus2 7 and Zeus T8
RL-505 - AMPS (Universal), Trimble GFX750
RL-506 - For Raymarine a6 and a7
RL-507 - For Garmin GPS MAP 700 Series / Echo Map 70s/ Garmin EchoMap 7 and 9 Series, GPS Map 7407, 7607
RL-513 - Universal self-drill top plate
RL-515 - AMPS & 3 point top plate - Topcon X25/X30/X35
RL-516 - 48mm diamond top plate - Loadmaster A50, Trimble CFX-750, EZ-250
RL-517 - 75mm square VESA top plate - Trimble TMX 2050
RL-519 - 120mm diamond top plate - John Deere GS2600/GS2630
RL-520 - 60mm square top plate - Krone Delta Control Box