Stahlwille Series 20 Double Ended Ring Spanners. Metric, drop forged from high-grade special steels and chrome plated. Manufactured to DIN 838ISO 10104. The spanners are optimally hardened in continuous furnaces with no scale build-up or skin decarburisation and gently quenched in oil. They are extremely strong yet lightweight due to Stahlwille’s ‘double-T profile’. The unique plating method prevents the problem of chrome flaking. The ring end of the spanners are equipped with an Anti-Slip Drive profile to permit high transmission of forces to the flats of the nuts and bolts without damaging them. Made in Germany.