Useful information: When using Q clamp 148 fittings for the top rail of a guardrail,the top of the upright must NOT be reduced in length but left at full height. The top of the tube will need to be capped using a Q clamp 133. Sold in pairs to create angles between 85° and 235°. A central tube is required to join the fittings together to create the angle. When working out the correct tube length dimension ‘C’ should be subtracted.