{"product_id":"ronstan-rf40171-series-40-ball-bearing-block-single-upright-lead","title":"Ronstan RF40171 Series 40 Ball Bearing Block – Single Upright Lead","description":"\u003cp\u003e\u003cstrong\u003eSeries 40 Ball Bearing Block - Single Upright Lead\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eLead blocks are a low profile solution for leading halyards or other rig sail controls back to cleats or jammers. Precision molded Acetal sheaves running on Acetal or Torlon ball bearings provide high performance  low friction. The 2-stage ball bearing system provides consistent performance over the full load range.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eApplications:\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\u003cli\u003eTypically used for halyards at the mast base.\u003c\/li\u003e\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eMaterials:\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eAcetal ball bearings\u003c\/li\u003e\n\u003cli\u003eUV stabilized Acetal sheave\u003c\/li\u003e\n\u003cli\u003eGrade 316 stainless steel load housing\u003c\/li\u003e\n\u003c\/ul\u003e \u003c!--- cis2:m2lsl5xp ---\u003e\n\u003cp\u003e\u003cstrong\u003eRonstan RF40171 Series 40 Ball Bearing Block – Single Upright Lead\u003c\/strong\u003e provides a low-profile solution for leading halyards and other sail-control lines back to cleats or jammers. Designed for sailors, riggers, and boat owners, this Series 40 ball bearing block supports efficient line routing in applications where dependable, low-friction performance and a compact profile are important.\u003c\/p\u003e\u003cbr\u003e\u003cp\u003eThe precision-molded Acetal sheave runs on Acetal ball bearings to help deliver smooth line movement and high performance. Its two-stage ball bearing system is designed to provide consistent performance across the full load range, making the block well suited for sailboat rigging systems. The single upright lead configuration is typically used for halyards at the mast base, helping route control lines toward accessible deck hardware.\u003c\/p\u003e\u003cbr\u003e\u003cp\u003e\u003cstrong\u003eKey Features:\u003c\/strong\u003e\u003c\/p\u003e\u003cbr\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFeature: Low-profile design:\u003c\/strong\u003e Provides a compact solution for leading halyards and other sail controls back to cleats or jammers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFeature: Two-stage ball bearing system:\u003c\/strong\u003e Supports consistent performance across the full load range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFeature: Precision-molded Acetal sheave:\u003c\/strong\u003e Promotes high-performance, low-friction line handling.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFeature: Single upright lead configuration:\u003c\/strong\u003e Suited to typical halyard routing applications at the mast base.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFeature: Marine-grade construction:\u003c\/strong\u003e Combines an UV-stabilized Acetal sheave with a Grade 316 stainless steel load housing.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cbr\u003e\u003cp\u003e\u003cstrong\u003eProduct Details:\u003c\/strong\u003e\u003c\/p\u003e\u003cbr\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Ronstan\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e RF40171\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Series 40 ball bearing block\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConfiguration:\u003c\/strong\u003e Single upright lead\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrimary Application:\u003c\/strong\u003e Halyards at the mast base\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSheave Material:\u003c\/strong\u003e UV-stabilized Acetal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBearing Material:\u003c\/strong\u003e Acetal ball bearings\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLoad Housing:\u003c\/strong\u003e Grade 316 stainless steel\u003c\/li\u003e\n\u003c\/ul\u003e\u003cbr\u003e\u003cp\u003eChoose the Ronstan RF40171 Series 40 Ball Bearing Block for streamlined halyard routing and reliable low-friction performance in sailboat rigging applications.\u003c\/p\u003e\u003cbr\u003e\u003cp\u003e\u003cstrong\u003eSEO Meta Description:\u003c\/strong\u003e Shop the Ronstan RF40171 Series 40 ball bearing block with a low-profile design, Acetal sheave, and two-stage bearings for halyard routing.\u003c\/p\u003e\u003cp\u003e\u003cb\u003eFeatures:\u003c\/b\u003e\u003c\/p\u003e\u003cul\u003e\u003cli\u003eLow-profile design for leading halyards and other sail controls back to cleats or jammers.\u003c\/li\u003e\u003c\/ul\u003e\u003cul\u003e\u003cli\u003eTwo-stage ball bearing system for consistent performance across the full load range.\u003c\/li\u003e\u003c\/ul\u003e\u003cul\u003e\u003cli\u003ePrecision-molded Acetal sheave for high-performance, low-friction line handling.\u003c\/li\u003e\u003c\/ul\u003e\u003cul\u003e\u003cli\u003eSingle upright lead configuration typically used for halyards at the mast base.\u003c\/li\u003e\u003c\/ul\u003e\u003cul\u003e\u003cli\u003eUV-stabilized Acetal sheave and Grade 316 stainless steel load housing.\u003c\/li\u003e\u003c\/ul\u003e\u003cstyle\u003etable.productattributes, .productattributes td { border-bottom: 1px solid #ddd; border-collapse: collapse; padding: 2px; text-align: left; }\u003c\/style\u003e\n\u003ctable class=\"productattributes\"\u003e\n\u003cthead\u003e\u003ctr\u003e\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\u003ctd\u003eTruck Freight: No\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eOversized: No\u003c\/td\u003e\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003cbr\u003e","brand":"Ronstan","offers":[{"title":"Default Title","offer_id":44881671258201,"sku":"70615","price":68.97,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0623\/1818\/2489\/files\/70615XL.jpg?v=1789193725","url":"https:\/\/www.marinepartsonly.com\/products\/ronstan-rf40171-series-40-ball-bearing-block-single-upright-lead","provider":"Marine Parts Only","version":"1.0","type":"link"}