I can't tell from the pictures but it appears that they are the same low end tang sight with a different base. The 1.5 inch base fits some rolling blocks the longer Sharps base is for Sharps rifles. Either one can be screwed to wood but stock of the BC. However, you should consider this. I have had some sights like these and they have only one up setting and if it is not perpendicular to the barrel both for and aft as well as side by side you are looking at problems. They can be corrected with shims though. You also need windage adjustments if you are planning to shoot at longer ranges. I can't tell if they have that or not. A better choice for a BC would be a tang sight with windage and elevation settings. They cost more but take it from me a cheap sight will frustrate you more than anything I know of.