Plugged a pigeon with it the other day with a good sized pebble ,the wood is ash ,as you can see the squares work rel good with the big stuff ,an lasts for a long time which i like the down side is it's real hard to get over here ,in fact some one from the UK sent the squares ,they are slower than most tubes i've used but they still hit with authority and as most Brits who've been shooting long they are game getters from way back think the origional Milbro's were ment to have squares for the lastic .