TC Encore Pro Hunter EER Scope Base Precision machined Extended Eye Relief (EER) scope base for TC Encore, Pro Hunter, Omega, Triumph and Impact barrels. Standard 4-Screw mounting with option for FREE 6-Screw mounting. Super rigid, precisely straight Weaver style scope base made by EABCO, the experts of T/C Encore and Pro Hunter rifles and barrels. Full width slots for locking into rings with more surface area, and repositioned slots for better strength and mounting convenience. Length-approx. 4.7"- Free 6-Screw Installation w/Purchase of a Barrel - Certainly this scope base will fit the standard 4-hole Thompson Center scope mounting system. But when you order it with a new barrel, we'll drill and tap two additional holes and do a full 6-Screw installation at no additional charge ($30 value).