The Toledo Compression Tester Kit is a professional grade set perfect for quickly and easily identifying compression related engine issues without the need for external connections. Unlike leak down testing which requires connection to an air compressor, this standalone unit can be used independently to ensure you have access to the information where and when you need it.This kit includes adaptors for 14mm and 18mm spark plug set-ups, and also features a 150mm long rubber cone-tipped steel extension that can be used for more universal applications. The dual calibrated gauge is easy to read and provides measurements in PSI and kg/cm, with a pressure release valve on the side to allow you to reset at any stage.