The Buckshot Racing #77 Water Pump Housing Adapter Sleeve is a direct replacement for the expensive Mercury OEM guide tube.
 
This big tube guide is made from a lightweight high-strength glossy 3K tow (3000 filaments-per-fiber) carbon fiber tube used in high-performance aerospace, automotive, and marine applications.
 
Our kit includes one (1) Carbon Fiber Guide Tube for the water Gen II pump housing. 

This Mercury 2.5 Liter Race Big Carbon Fiber Adapter Sleeve fits all big tube water pump housings including; 260 ROS, 280HP, 300 Drag, 225 EFI PROMAX and SUPERMAGNUM, 225 EFI PRO MAX/SUPER MAG, 150/200 PRO-MAX/SUPER MAGNUM (EFI), 2.5L EFI, 2.5L EFI OFFSHORE, MERC/MARINER 2.5L (EFI), HI PERF MERC/MARINER S3000, SST 120 S2000 Opti 200XS, FORMULA 1 2-LITRE (EFI), 200XS SST200, XR-2 MAGNUM, and Mercruiser applications.
 
It Replaces the Adapter Sleeve for the Water Pump Housing on all Mercury 2.5L Race Large Tubes with the OEM part number  847685