I have a Dr Bob adapter and Sony VCL-HG1737C 1.7x lens doubler for the Pulsar N550. This increases the magnification from 4.5 x to 7.65 x with no loss of zero if correctly fitted.
The Dr Bob adapter is worth £30 and the Sony Lens is worth £130. I will sell both for £110 including P&P.
The Sony lens are well known for being better than the Pulsar lens "doubler" that are also for sale.