Easily determine the dimensions of your rod and cylinder bores with these handy Proform dial indicators. Proform's Universal Dial Indicators are available in three different sizes 0-1", 0-2.5", & 2-6" with graduation of 0.001". The 2-6" is the Professional Dial Bore Gauge that features an extendable handle all protected by a durable carrying case. Also available separately is the Proform Universal Magnetic Deck Bridge will go over cylinder bores up to 4-1/2". This is used to check piston-to-deck clearance. Because it is magnetic it will hold firmly in place.