Revolver Scope Base Rail for Anaconda Python Taurus 689 with 6- 8 non-ported vent rib barrel A revolver scope base rail in stainless chrome silver finish for the above-listed revolvers. The rail has 19 ring slots, which make it easier to set up eye relief and find more desired placement of scopes or red dot sights on top of the revolver. No drilling is needed. The scope rail is clamped onto the vent rib of the non-ported barrel of 6 to 8 using the hex screws and two steel tabs. The steel tab goes through the openings underneath the vent rib and clamps down by tightening the hex screws. Top rail is compatible with Weaver-style rings and also will mount red dot sights with a Weaver-style mount. Machined from extruded aluminum alloy. Mounting screws are included with the unit. Rail type: Weaver Number of ring slots: 19 Overall length: 7 1/2 Finish: Anodized matte stainless silver Weight: 2.8oz * When mounting the rail onto the revolver, the cantilever end should be pointing toward the hammer side. Check alignment of the rail with the center line of the barrel before tightening the clamping screws. Always be sure to unload and practice safe gun handling when mounting the rail.