Product Details: self opening coventry die headSize1/2ColorNormalBrandSMTMaterialHSS(High speed steel)???Coventry die heads and copies thereof (Rubometric, OSG etc) are the most commonly used thread cutting die heads.???They are reliable, hard wearing, simple to set and use, and can be used on manual or automatic ( and CNC) machinery.???Maintenance and repair can be easily carried out in house, chasers are cheap and thread changeover is fast and easy.CH Style:???Very similar to the original C Style but the shank is separate to the rear of body.???Can be used on all manual machinery, popular with model makers.???Not really suitable for automatic machinery as little spring loading to assist head onto work piece.???Threaded spare parts (screws etc) are expensive due to use of non standard threads.CHS Style:???Shank sprung to body making it ideal for automatic machinery.???Adjustment by two socket screws.???Most popular Style of Coventry die headDX Style:???Fitted with external trip to open die head at end of thread. This is to overcome a problem that can occur with C, CH & CHS die heads when cutting short threads in soft materials. In such cases the weight of the head pulling against the thread in opening can strip the thread.External trip also ensures very accurate thread length.???Can be operated in ''pull off'' mode same as other heads.???Designed for automatics so fitted with spring band closer.