These plastic or rubber parts are used under many of our parts, keeping them from touching the drum shell. Why are these so much higher than our other gaskets? We, just discovered that this supplier is charging us MUCH more than others do for this item - so the price here is very close to our COST. Parts noted Slingerland style mean that they look a bit like the Slingerland parts, the hole spacing fit could vary. There are no standard there. If you are trying to retrofit a Slingerland drum, make sure to measure your holes to compare for a fit.