508 mm stringing blocks are normally used for stringing medium size conductor (17-25 mm) in overhead transmission line construction. We have designed series of these stringing blocks for single conductor, 2 bundled conductor and 4 bundled conductors stringing. 1.Maximum suitable conductor ACSR400.Configuration: 2.Sheave dimension ( outside diameter× root diameter × sheave width) Φ508×Φ408×75 (mm) 3.Sheave dimension Φ508×Φ408×100 (mm) can be customized